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Why Most People Are Sleep-Deprived and What to Do about It


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I’m excited to have Dan Pardi as a guest on today’s show. I met Dan at PaleoFX last March, and we instantly hit it off. As a PhD candidate sleep researcher at the University of Leiden in the Netherlands, and the CEO of Dan’s Plan, Dan is one of the most knowledgable people on the effects of sleep on health I’ve come across. I hope you enjoy the interview!

In this episode, we cover:

6:48 Why sleep is essential to health
20:30 The telltale signs of sleep deprivation
32:40 Does light play a role in getting better sleep?
40:28 The truth about polyphasic sleep
49:00 Simple tips for getting better quality sleep

Full Text Transcript:

Steve Wright:  Hi, and welcome to another episode of the Revolution Health Radio Show brought to you by ChrisKresser.com.  I’m your host, Steve Wright from SCDLifestyle.com, and with me is integrative medical practitioner, licensed acupuncturist, and healthy skeptic, Chris Kresser.  How’s it going?

Chris Kresser:  I’m doing pretty well, Steve.  How are you?

Steve Wright:  I’m pretty jacked tonight.  We have a very special guest on the line.

Chris Kresser:  Yeah, I’m excited to introduce Dan Pardi.  Dan and I met at Paleo f(x).  Actually we had been on each other’s radar before that, but we finally met at Paleo f(x), and we hit it off right away.  I think we share a similar perspective on a lot of this stuff, and we spent some time together and got to know each other, and then we hung out a little bit at AHS, and we’ve become fast friends.  And so, I have a lot of respect for Dan and his work, and I’m really excited to have him here on the show, and I’m gonna have Dan introduce himself and tell you a little bit about how he came to this work and what his perspective is.  And then we’re gonna spend the rest of the episode talking about sleep.  So, Dan, why don’t you say hello to everyone and tell them a little bit about yourself and where you’re coming from.

Dan Pardi:  Great.  Thanks for the introduction, Chris.  I tell you, it’s a real honor to be here because I learn so much from you and this podcast, so it’s a real pleasure.  And I’m excited to talk about some concepts related to sleep today, and yeah, I’ll tell you a little bit more about myself.  So I’m a researcher, and I work with the Department of Neurology and Endocrinology at Leiden University in the Netherlands, and I work with the Behavioral Sciences Department at Stanford University.  And I look at how chronic sleep deficiency or not getting enough sleep on a chronic basis, how that affects things like decision making and weight gain, just a couple of areas that have been of interest to me for a long time.  I got into sleep probably 10 years ago.  I was working at a pharmaceutical company that was working in rare disorders and had a sleeping drug for narcolepsy.  And with that, I started going to scientific conferences on a yearly basis and was just trying to soak up as much information as I could because as soon as I started to learn about it, the doors opened up and I couldn’t learn enough.  It’s an endlessly fascinating topic, I find, and how it leads to personal insight about yourself or others, our health.

And so over time I started to think about — I had done some academic research in the past on lifestyle factors like diet and stress management and exercise, and a lot of these different disciplines that I had explored started to coalesce into some ideas about how to help to facilitate health in others, and I created this model for behavior change, and the idea was that it would look at a variety of different influences on behavior and try to harness those in a way that would enable somebody to live a healthy lifestyle more easily.  And from that I started to try to operationalize the model, and friends called it Dan’s Plan because I had talked to them about what I was doing, and the name kinda stuck, and it seemed memorable so I rolled with it.  Yeah, so now the idea with Dan’s Plan is simple:  We try to take the best practice guidance about what is the information that is most helpful to help us live in a way that is going to facilitate health and try to filter it through this behavioral model, which uses things like behavioral economics and persuasive technology, and the idea is to try to simply a person’s health practice to try to make it as easy as possible for them to live a healthy lifestyle on a day-by-day basis.

So, that’s what we do, and one other thing that I’ll say is that the thesis that we’re working off of is that a lot of modern illness is a result of what we call a broken lifestyle, and that is a lifestyle that is in discordance with our biology and because this is facilitated by a lot of modern luxuries.  So instead of having a lot of our health behaviors be predicated on survival behaviors, we now have an option to really not engage with things that keep us healthy.  And so, therefore, if you want to be healthy, you have to cultivate and maintain a personal health practice because right now we actually have the option not to, and so we try to look at what are the things that make that health practice effective to keep you free of disease, maintaining full physical function, and have the highest quantity of health within your lifespan.  So that’s a little bit about me and what I do.

Chris Kresser:  Cool.  Thanks, Dan.  And for the record, everybody, Dan’s Plan is excellent.  I recommend it to all of my patients.  It’s the best tool that I know of for tracking the most important factors in changing your lifestyle and meeting your health-related goals, and it’s completely free, so you should definitely go check it out.  It’s at DansPlan.com, and you can set up an account.  You can set up your weight goals and your sleep goals and your movement and activity goals, and then there are a lot of really cool tools to help you stay on track.  There are great emails that he sends out every day with suggestions for exercise and activity and recipes and other hardware tools that interface with Dan’s Plan like the Fitbit and the Withings scale that can make it really easy to track your data and get it up into Dan’s Plan.  So, definitely check it out.  I think it’s definitely the wave of the future in terms of this kind of tracking.

Dan Pardi:  Thank you.  Thanks, Chris.

Why sleep is essential to health

Chris Kresser:  OK, Dan, so let’s begin by talking about some fundamentals of sleep because I think even though sleep, you know, we talk about it a lot, we hear about it a lot, I think everyone knows a little something about the importance of sleep, there are still some things that we don’t know about sleep, and I find that pretty interesting after all this time researching it.  But let’s begin with why do we even need sleep, how does it work, and what are some of the key metrics to consider when we talk about measuring sleep.

Dan Pardi:  It’s a great question.  You know, this question of the purpose of sleep has really been elusive to researchers, and I think it might actually have to do with the nature of the question itself, as though we’re trying to identify a singular purpose for sleep when really there might be hundreds of purposes to sleep, many, many things that it does to kind of work in a reciprocal fashion to what’s happening during the day so that we are better prepared for the next day once we engage with sleep.  So yeah, that kind of grand purpose, it still eludes us, and it’s like every scientific study concludes with “more research is needed.”  You know, every time you go down one path, it opens up more doors, and that’s perhaps the frustrating thing about science but also one of the wonderful things, too.

So, the structure of sleep is it’s very complex and active and highly organized.  We used to think that sleep was just this period of behavioral quiescence, so the mind and the body kind of shutting down and relaxing, but we know now that there are parts of the brain that are more active during sleep than they are at any other point during a 24-hour period.  We also know that the structure and the sequencing of the sleep stages — There are different sleep stages that we go through over the course of the night, and different research will look into, you know, what are the important aspects of these different stages, how about the rhythmicity, so how they flow together.  And the three real kind of cardinal features about sleep, the keys, are timing, intensity, and duration.  And there’s so much more to talk about, but those three things are really critical.  So, timing has to do with your bedtime and your wake time, so that timing within a 24-hour period.  Then there is duration.  OK, that’s easy.  That’s the length of time that you sleep within that period.  And then also intensity, which refers to the depth of sleep, and you could spend 8 hours sleeping and if you only stay in the lighter stages of sleep, you’re not gonna really reap any benefits of sleep, so you’re gonna wake up feeling like you got no sleep at all and you’re gonna feel that way, too.  So the depth of sleep has been looked at as a marker of quality, but it really has to do with both the depth of sleep, the cyclicity of sleep, so there’s definitely a lot kind of going on there, and the whole conversation would be about just looking at these different structures, but I think that’s probably good.

Chris Kresser:  Um-hum.  And there are certain health conditions, like I think there’s some pretty interesting research about fibromyalgia and nonrestorative sleep where a lot of people with fibromyalgia are only getting, you know, in stage one, stage two, maybe some stage three, but they don’t go into deep sleep, and their muscles are never able to fully restore themselves, so they have this constant soreness as a result, which I’m sure a lot of people can relate to if you’ve had a few nights of poor sleep, what happens to your muscles and your recovery after that period of time.

Dan Pardi:  Yeah, that’s right.  Sleep can be truncated, so you can lose sleep by just simply not being in bed long enough, you can miss out on certain stages, or then the architecture or that rhythmicity that I was talking about, so how the stages flow back to back, that can be disrupted, too.  And all of it can lead to these cardinal features of poor sleep, so feeling sleepy, mental impairment, physical impairment.  So it can get disrupted in a variety of ways, but achieving good sleep is also something that a lot of us can do when we kind of do the right things on a daily basis, and we’ll talk about that further.

Chris Kresser:  Yeah, let’s talk about that in particular because I read something a couple days ago, I think, that a third of Americans are getting less than 6 hours of sleep a night, which just strikes me as, like, an alarming epidemic, probably one of the most shocking statistics I’ve heard recently.  And if we want to talk about things that are gonna send our health off of a cliff, of course we talk about diet and lack of physical activity and things like that, but I’m thinking that this single statistic is probably scarier than anything else in terms of its potential impact on our health.

Dan Pardi:  Yeah, we’re getting 20% less sleep per night on average than we were 40 years ago, and these are statistics from the National Sleep Foundation, which does sleep polls every few years.  So around in the 1960s, average sleep times were about 8-1/2 hours per night or least times in bed or self-reported sleep times.  And there was an assessment of subjective sleep time in the early 1900s, and it was about the same as it was in 1960, so about 8-1/2 hours.  And there has been a slow and steady decline in sleep times, and now the average is 6-1/2 hours per night for working adults, and then about 7 hours and 20 minutes on the weekends and trying to play catch-up.

Chris Kresser:  And that doesn’t even reflect the quality of sleep, so it’s possible that those 6-1/2 hours, it’s not only shorter than our traditional norm, but those 6-1/2 hours are poorer quality, I would suspect, than they have normally been.

Dan Pardi:  Well, it’s very possible.  In some senses, sleep has the ability to almost compress, so it’s compensatory in that when you get less sleep one night, the staging, the depth of sleep will try to do its best to try to get that sleep back, to try to recover lost sleep.  But there are also these factors, you know, like one big important factor is light in our environment.  In fact, artificial light is listed as a probable carcinogen by the World Health Organization.

Chris Kresser:  Wow.

Dan Pardi:  And I think that’s because when we have a lot of artificial light in our homes, we’re staring at iPads and TVs, right?  We’re getting engaged.  Light will directly stimulate the cortex, and it acts like a cup of coffee.  So it’s this fallacy to think, well, I’m gonna just read my iPad until I’m sleepy, right?  Because it’s keeping you up.  And so, even if you’re getting less sleep on a nightly basis, this sleepiness is getting masked by the environment in our homes in the evening, and that can then set your circadian rhythms, which we’ll talk about in a little bit.  That can get them off so that the necessary rhythms in the body become out of synch, and there are very real consequences to that, including much higher incidences of cancers, coronary heart disease, metabolic disease like diabetes.  So yeah, I agree with you, Chris.  I think that this is one of the most significant issues that we’re facing in our health today.

Steve Wright:  So when you’re talking about the artificial light and we’re talking about decline of 2 hours plus or minus a little bit from the ‘60s, which I wasn’t around in the ‘60s, but I hear they didn’t have iPads and the TVs were, like, a different type.  They were round or something.  I guess it was weird.

Chris Kresser:  And they weren’t 70 inches on the wall?

Steve Wright:  Yeah, yeah, like the programming stopped at night or something and people went to bed.

Chris Kresser:  Yes.  Imagine that.

Steve Wright:  Yeah, so I’m just curious, do you guys really think that the extra 2 hours is also technology based?  Are we compounding it?  We’re losing hours in bed and replacing those with artificial light hours?

Dan Pardi:  Well, there’s probably a variety of things that are culpable in why we’re getting less sleep.  One of them, I think a very real issue is our technology because it will mask the sleepiness.  Not only is the light going to keep you up and be an artificial stimulant, but also what are you doing?  You’re maybe doing work, playing Angry Birds, whatever that is — that’s going to engage you and mentally stimulate you as well, so that’s one thing.  But then there are also things like longer work times and longer commute times, and so to some degree, people are trying to just find more personal time for themselves and their family, and they’re getting home at 8 o’clock at night, and they want to have a little time to themselves.  So there are those sorts of factors that are also kind of shaping, I think, this new existence.

Chris Kresser:  You think there’s been a cultural shift, too, you know like this kind of idea of I’ll sleep when I’m dead and a lot of the biohacking ideas out there where folks believe that they get by just fine on 4 hours of sleep, you know?

Dan Pardi:  Yeah.

Chris Kresser:  I don’t know.  I mean, those trends seem to have been around for a while.  I can’t imagine that kind of conversation was happening in the ‘60s.

Dan Pardi:  Yeah, I don’t know.  It’s interesting, and I don’t know.  I don’t know how new they are, but there is that modern mindset of just trying to maximize performance over your day.  You know, there’s so much that’s being asked of you.  And people sending work emails at, like, 2 in the morning, and there’s probably some subconscious communication about look how hard I’m working, look how dedicated I am.  But then there’s also, like, hey, look how well I can do with less sleep.  It’s almost like a bravado as well.  So there are a lot of different forces that are shaping this, and some of them are kind of, again, subconscious, and some of them are more the mindset that we’re operating under.

Chris Kresser:  Yeah.  I think there’s a boundary issue with the way that — You know, one of the benefits or the promises of modern technology is that it sort of untethers us from the traditional office environment and 9-to-5 work schedule, but one of the downsides of that is that now, as you’ve pointed out, you can be on vacation, you can be at home at 10 at night, you can be at home on Sunday or out doing errands and there are work emails coming in if you have your phone set up for that, which a lot of people do.  And so, you pretty much never have a break, if you do set it up that way, from work, and I think human nature, it’s hard for a lot of people to resist that.  If it’s possible, a lot of people will do it.  So I personally feel like that has a huge impact on people’s sleep rhythms and just their ability, as you said earlier, if they’re on their iPad and they’re doing something and an email pops in at 10 o’clock at night, it may be hard for them to resist checking it, and then they check it and it’s like a big fire at work that needs to be put out, and so all of a sudden they’ve shifted into a state where they might have been relaxing and kind of getting ready for sleep into like an activated stress response because of something that’s happening that’s work related.

Dan Pardi:  I was thinking about something very similar earlier today, Chris, and I agree.  In some senses, yeah, it’s this great benefit of untethering us from just being at a desk 9 to 5, but then it follows us everywhere.  And I think the only real vacation these days is the one without cell reception.

Chris Kresser:  Haha, that’s right!  Yeah, I purposely look for places like that at this point.  They’re harder and harder to find, though.

Dan Pardi:  Yeah, so I think what’s gonna happen is there needs to be some public awareness about some of the negative consequences, particularly within work environments, so showing the employers that if you want a really good, happy, productive person, they need rest, they need an off period, and you have to make it somewhat part of the culture to regard sleep as something that is going to help you perform on a daily basis.  You know, like you wouldn’t go to work and have a glass of alcohol.  It’s just not culturally acceptable.  And so, I think getting sleep time and not sending emails really late at night, that’s going to, I think, hopefully imbue into kind of the work culture and so there will be less pressure to kind of confirm to what your workmates are doing.

The telltale signs of sleep deprivation

Chris Kresser:  Um-hum.  So let’s just dive in a little more deeply to the consequences of sleep deprivation.  I mean, I’m sure most of my listeners have a pretty decent idea just even from their own personal experience, but the research on this is robust, and it’s pretty scary, actually, so tell us a little bit about what you’ve seen in your research and just your awareness of the overall body of literature.

Dan Pardi:  Yeah, the effects of sleep will affect almost all body systems and tissues, and I think we’re still uncovering and unraveling the effects of sleep loss on our health, and I think there’s probably some impairments and consequences that are taking place that we’re not even fully aware of.  But you see very meaningful, consistent clinical data showing cardiovascular risk, metabolic risk, premature aging and cancers, problems with the brain, so it’s almost hard to find some tissues or systems that aren’t really affected with chronic sleep loss, but then again, it’s also newer, right?  So we’re getting less sleep as a society, and it’s continued to go down over the last 20 or 30 years, and so right now we’re at the lowest average that has ever been recorded, and so the results of today, it’s unprecedented.  We don’t know what’s really gonna happen and how severe it can be.

Chris Kresser:  Really it’s a big society-wide experiment.

Dan Pardi:  Yeah, exactly.  That is life today, haha.

Chris Kresser:  In a number of respects.  So how about more particularly on weight regulation?  I saw a pretty interesting quote — I think you sent it to me — from a study that said in that study sleep deprivation was more of a risk factor for obesity than fat intake or lack of higher intensity exercise.

Dan Pardi:  Yeah, this has been a line of research that has gained a lot of visibility over the last probably 10 years, and it started with — There were several different studies, but one of them was the Wisconsin Cohort, which looked at 15,000 people and noticed that if you did a trendline, those that actually slept less tended to be higher weight and had a much higher risk of being overweight, and it was actually this sort of U-shaped curve.  So the extreme long sleepers, they also actually had higher weights as well, and the average right around 8 hours was the people that maintained the lowest weights.  And so these studies were followed up with short prospective-term studies where they took healthy young men and they would subject them to, you know, 4 hours of sleep per night, and then they would monitor some of their homeostatic hormones like leptin and ghrelin, and they noticed that both leptin and ghrelin, which affect feeding, energy regulation, sympathetic nervous system activity — all things that will eventually help to control or influence body weight — would adjust in a manner so that you were more likely to be hungry and more likely to be storing fat, and less likely to be burning energy.  So that’s been followed up multiple times both in animal studies and in humans, and additionally we also see that there is a pretty immediate and significant impairment in glucose regulation.  So the thinking is that chronic sleep deficiency is going to not only predispose you to obesity, and by the way, 81 out of 89 studies that have looked at this have found positive findings, and the risk seems to be that lack of sleep or chronic sleep restriction will increase your risk for obesity about 55%.

Chris Kresser:  Wow.

Dan Pardi:  So it’s really, really meaningful, this connection.  How it’s happening, I think, is still being discovered.  But certainly, you know, the sympathetic nervous system is an autonomic process that will be much higher during the day or when you’re awake, excuse me, more active during wakefulness than it is during sleep.  And so, as we truncate our sleep times, you’ve got longer periods of the sympathetic nervous system activity, which might have this downstream effect on cells or on cortisol.  One of the downstream effects actually is cortisol, and we know that if you have higher levels of cortisol circulating, like Cushing syndrome, you can induce insulin resistance and rapid fat gain.  So those of some of the areas that have been explored, but there either seems to be a clear connection between sleep loss and weight gain, and also there seems to be one between sleep loss and the increased risk of diabetes, as well.

Steve Wright:  Hey, Dan or Chris, one of you two guys jump down that rabbit hole, so when poor sleep or chronic low sleep messes up my ghrelin or my leptin, which one’s gonna be appetite regulation, the other one’s gonna be appetite regulation as well kind of, tell us when we’re not sleeping correctly, tell me what’s gonna happen during the day, what body functions are gonna malfunction because of these hormones?

Chris Kresser:  Dan, maybe you could address that in relation to your research on sleep and appetite and decision making.

Dan Pardi:  Yeah, sure.  These hormones will display 24-hour cycles, and so leptin will gradually rise from the morning over the course of the day, and then it will peak somewhere in the evening, and ghrelin will follow a little bit of a different pattern.  It’s considered an episodic hormone, in that it waxes and wanes depending on food intake over the course of the day, but it also seems to peak in the middle of the night and then decrease.  And ghrelin is a fascinating hormone, actually, because it’s released from what are called oxyntic cells in the stomach, and it’s thought that it will stimulate hunger.  So when there’s lack of food in the system for a period of time, ghrelin levels rise, and then that will make you hungry.  But it also is then involved in things like reward, so it has a lot of effects on cognition as well, and it’s involved in memory and reward processing, so anyway, lots of interesting stuff that’s going on there.

But there’s different ways that this can kind of be messed up.  When you have less sleep, you actually affect the daily rhythms of both of those hormones, so with 2 hours less sleep per night, there’s about a 15% decrease in leptin and about a 15% increase in ghrelin, so one goes up, one goes down.  Both of them, again, would predict that you would be hungrier, and that is what some research has seen, is that people tend to be a little bit more impulsive and they tend to crave what’s usually found is high-carbohydrate food.  And that may or may not be true, but what my research is looking at is, is it that they’re craving high-carbohydrate food or are you actually just more impulsive?  And a lot of high-carbohydrate foods in our cupboards, for example, they tend to be:  open package, eat.  Right?  In the typical American home.  So is it the carbohydrates or is it kind of the quickness?  You know, it’s many more steps to prepare a meal, but just opening a drawer and eating something, what we know is that sleep loss makes you much less likely to make an effort for a reward.  And it’s called effort discounting.  And so, you just want to basically find the fastest path to make you happy because you don’t want to work for it.  So that’s what my research is looking into.

And I’ll share another example that is not specific to weight gain but is really interesting, and I won’t go too nerdy here, but I’ll mention these two parts of the brain.  So one of them is called this ventral medial prefrontal cortex, and it actually is a part of the brain that is known for what’s called the neural correlate, so this is the area of the brain that is thought to represent the estimation of gains, so if you’re in any sort of risky decision making, like gambling, right?  If you’re about to say how much can I win?  Then this area of the brain is very responsive.  A counterbalancing part of the brain is called the anterior insula, and that’s thinking about all the consequences of gambling.  And when you’re sleep deprived, then the area that is encoding possible gains becomes very active, and the area that’s encoding possible losses becomes not very active at all.  So if you think about when casinos make a lot of their money, it’s late at night, right?  You’re sleep deprived, right?

Chris Kresser:  Yeah.

Dan Pardi:  Probably you have alcohol in you, too, if you’re in a casino.  And you’re much more likely to make a gamble that you ordinarily would never do.  Now think about how that translates into everyday life where in this obesogenic environment there’s food everywhere.  Are you less likely to say no to the candy bowl as you pass it?  You’re not thinking about the consequences.

Chris Kresser:  That explains why people eat that food at the casino buffet.

Dan Pardi:  Something has to explain that!

Steve Wright:  Does lack of sleep also lower dopamine?  Like, are these people also kind of craving a possible dopamine hit?  Is that part of it?

Dan Pardi:  It’s an interesting question.  You know, this guy David Rye is one of the foremost dopamine researchers in the world, and he — It’s funny, haha.  It’s a good question.  He would roll his eyes at it because he gets really frustrated because dopamine doesn’t do just one thing in the brain.  Actually the levels stay relatively constant, particularly compared to other neurotransmitters, particularly over a 24-hour period.  And in some areas it’s promoting inhibition, in other areas it’s more excitatory, so it’s hard to think of dopamine as doing one thing.  It actually is having kind of pervasive effects throughout the brain as basically a signaling molecule.  But we do tend to think of it as being related to pleasure and reward, and there is some idea that that might actually be a possibility, and we do know that one thing that does affect dopamine signaling is light, so as you can see with seasonally obese animals — these are animals that become obese during certain parts of the season — you’ll see a drastic reduction in dopaminergic signaling in the master clock in the brain.  So dopamine signaling goes way down, and that probably has been signaled by alterations in the light-dark cycle as the seasons change.  But the corresponding change in the brain is there’s this big increase in noradrenergic or norepinephrine, another neurotransmitter in another part of the brain that is involved in feeding.  And so, in these animals, without any increase in food intake, you see the induction of metabolic syndrome.  They become hypercholesterolemic, they have insulin resistance, they gain weight immediately, and basically this is the mechanism by which the brain helps them store energy for the winter.  So could that actually be happening with us with these altered light-dark cycles?  And we’re not seasonally obese animals, but we also don’t really fully appreciate or understand the effects of the seasons on our health and our rhythms because it’s just hard to study.  So I’m not sure if that answered your question, but yeah, it’s some interesting dopamine research.

Steve Wright:  Yeah, super interesting.  Wow.

Dan Pardi:  Yeah.

Does light play a role in getting better sleep?

Chris Kresser:  So let’s talk a little bit more, we touched on this before, but about exactly how light does influence sleep rhythms and hormones that regulate sleep like melatonin and cortisol.

Dan Pardi:  Yeah, so light will enter into the eye, and it affects the specialized cells that are called intrinsically photosensitive retinal ganglion cells — not important, but a nice long scientific word.  And those will transmit their signal back into the hypothalamus, which I’ve heard you talk about, of course, on the show before.  And near that hypothalamus is this suprachiasmatic nucleus, the SCN, and that is the master clock in the brain — and the body.  So this is affecting the rhythms throughout the body.  And the way that it works is that that master clock, through the communication of light through the eye, will synchronize to the light-dark cycle of a 24-hour period.  So the clock in the brain synchronizes with the environment, and then all of the clocks — because there’s a clock in all cells in the body — will then synchronize with the master clock.  So there’s two synchronizations taking place:  our brain with the environment and then the clocks throughout the body with the master clock in the brain.  And what you see is that we know that at certain times of day, of course at night, melatonin levels go up, body temperature starts to drop, cortisol levels are low, and what happens is at different parts of the day there are different phase relationships.  So usually if you go to bed hours later than you used to, you’re gonna end up sleeping in a different hormonal milieu, right?  A whole different hormonal soup than you would if you have gone to bed at the time that you usually do.  Now whether or not that is pathological — I think that there’s some evidence that suggests that it is, but that is one thing that is — I’m suspicious of that.  But anyway, that is one way that light enters into the eye and affects these rhythms.

Steve Wright:  So is it all light?  I’ve heard a lot about this just being a blue light problem.  Or is it any light?

Dan Pardi:  Yeah, it’s a great question, because there’s definitely an emphasis in discussions around this around blue light, and the spectrum of light does matter.  But the things that do matter are the intensity of the light, the wavelength or the spectrum, and then the duration or how long light is acting on the eye.  So the intensity is actually very — If there’s any light at all, then it’s entering your eye.  If you can see at all, light is entering your eye and it has the potential to affect your rhythms.  But most potently, blue light will affect your circadian rhythms more than anything else.  So you can think of, well, during the day we’re getting a lot of bright, blue light, which makes sense being outside.  That’s going to, again, be a direct stimulator of cortical activity.  So if you want to feel like you’re having a cup of coffee, get outside, walk around, get some light in.  And outside light is much strongly intensity than inside light, and more so than it even appears so.  The intensity of light is measured on a logarithmic scale, so outside light is measured in lux, and it can be over 100,000 lux, where in a room inside light is 200 lux, so it’s much, much lower in intensity.  And intensity definitely shifts our rhythms.

And we know that if you’re outside during the day, then you’re gonna have a much more robust melatonin rhythm at night.  So being inside during the day will decrease your melatonin at night by about 50%, so what we end up having is this process unfortunately of asynchronization, and what I mean by that is we’re spending a lot of our time indoors during the day, right?  With not a lot of light and not a lot of physical activity.  And then in the evenings, we’ve got a lot of artificial light and a lot of things that are stimulating and keeping us up.  And at night, we might have also clocks and windows open and other sorts of light, a nightlight on.  That itself can also suppress melatonin.  So not getting enough daytime light will suppress melatonin, getting too much night-time or evening light will suppress melatonin as well, and so overall — You know, we know melatonin is a really fascinating hormone.  It has a lot of potential positive effects, particularly on cancers, and it is an antimicrobial agent.  And if we’re getting the natural amount of darkness in a natural living environment is somewhere, depending on the seasons, like, let’s say 10 hours, we’re not getting 6.  We’ve truncated that by 4 hours per night.  We’re not getting the benefit of that hormone acting throughout the body and having the ability to kind of exert its benefits.

Chris Kresser:  Yeah, and that’s, of course, what you described:  not enough light during the daytime and too much light at night.  That’s probably one of the primary factors of the modern lifestyle that’s driving this sleep epidemic.  Someone who goes to work in an office and is exposed to artificial light or very little natural light during the day and then they go home and the iPad and all the various technological devices emitting light, and it’s kind of a double-whammy effect.

Dan Pardi:  Yeah.

Steve Wright:  Dan, so what Chris just talked about, I’m sure a lot of listeners, including myself, are in that situation.  Is there is a minimum level of daytime light we should try to achieve?

Dan Pardi:  You know, that’s a really interesting question, and I don’t know we have an answer to it.  What is that minimal threshold that we need to surpass in order to maintain these normal rhythms?  Well, I would say that getting morning light is definitely important.  That serves as an anchor.  So I think waking up in the morning, getting outside, and getting light for a good 10, 15, or 20 minutes is a really smart thing, particularly if you do any fasting, by the way.  I do intermittent fasting myself, and I think that there’s some really interesting science behind it.  I know it’s not for everybody, but I’ll just bring it up to mention that if you do do fasting, then it is important, I think, to get bright light exposure first thing in the morning, because what a lot of people might do if they’re fasting is that their circadian rhythm will shift, right?  The body is always trying to listen to understand what part of the day are we in?  Like if you travel to Europe or basically you change time zones, over time, the body is taking in signals, not only light but also sleep, physical activity, food, those to a lesser degree than light, but they are affecting the circadian rhythms.  They’re gonna eventually help you shift and get onto that schedule where that schedule now feels normal.  So all of those things really do matter, and actually you see this in people that will do fasting for religious purposes.  What happens is that — it’s usually a month long — over the first couple of days, they basically shift their schedule.  So even though they’re fasting, they’re able to eat at night, and so they end up being up at night much longer than they normally would be if they weren’t fasting.  So be careful of that.  Get a lot of bright light exposure if you do fasting, particularly in the morning.  And then I would also say getting outside a couple of times a day whenever you can does make sense.

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The truth about polyphasic sleep

Chris Kresser:  Um-hum.  So I’d like to move this into a more practical direction, but before we do that, I want to talk a little bit about biphasic and polyphasic sleep.  I know we both saw this article in the New York Times last Sunday — maybe some of you all saw it — that was saying that we don’t really need 8 hours of continuous, uninterrupted sleep and that from an evolutionary perspective that probably wasn’t natural.  So what do you think about that, Dan, and if that’s even true and how applicable it is to our modern situation?

Dan Pardi:  Yeah, so the author, David Randall, wrote an interesting article, and there are a few things that I thought were really good points, and there were a few things that I thought were not accurate.  And this is actually similar — A BBC article came out probably six or eight months ago, and it was very similar to this, and it talked about this first and second sleep.  And it was referencing the work of a historian from Virginia Tech — I’m trying to remember his name.  It’s Ekirch, I think.  And this researcher was looking in historical texts, and he kept noticing references to this first period of sleep and second period of sleep, and basically what he identified is a natural sleeping pattern for people pre-Industrialization, pre-modern lifestyle, where they just had candlelight, is they would go to bed soon after sundown, they would sleep for a period of time, then they would wake up and have this alertness in the middle of the night, and then they would go back to sleep and sleep for the remainder of the night.  And both articles seemed to suggest that that is the more natural pattern, and they used that as a way to condemn the 8-hour monophasic, consolidated chunk of sleep.  And I don’t think that the evidence supports that.  Right?  Just because there are suggestions that an alternative or another pattern of sleep and wake might not have any harm, you’re not necessarily condemning the 8-hour monophasic sleeping in one 8-hour chunk.

Chris Kresser:  Right.

Dan Pardi:  The point that he brings up is that when you get really concerned about getting your 8 hours, it can cause anxiety, and without a doubt, that’s a good point.  Cliff Saper, who is the Dean of the Harvard Neurology Department, said insomnia is an anxiety disorder.  First and foremost, that’s what it is.  And people get worried about something, and they start to ruminate on an idea, and then eventually whatever was the kind of instigating stimulus that stimulates the insomnia, eventually it can just turn into this positive feedback loop.  Now you’re worried about the insomnia, and that’s preventing you from sleeping.  So anxiety is a problem, for sure, for people that have insomnia.  And we all experience that every once in a while, in some people for frequently, for sure.   But I think that, as we discussed earlier, the real problem in our society is lack of sleep, so we’re not getting enough sleep on a nightly basis.  At least it seems that way.  And we’re getting enough sleep to a degree that we will see very significant impairments in cognition if you were to look at those same situations under lab conditions.  And so, an awakening is not an awakening.  Right?  If you are getting all the sleep that you need and you wake up in the middle of the night, OK, then that’s fine.  You don’t necessarily have insomnia.  But if you are not getting enough sleep and you still can’t sleep, then that doesn’t mean that you don’t need that sleep.  It might be that you have temporarily a sleep issue.  So I think that there were a couple points that weren’t made as well as I would like for him to have.  What were your thoughts on the article, Chris?

Chris Kresser:  I thought it was just an interesting historical perspective, but I didn’t really see anything in there — I mean, even if we’re talking about pre-Industrialization, that doesn’t necessarily give us any insight into what was happening pre-Western civilization.  And I think obviously we’re in a really different place right now, and so even if a biphasic sleep pattern worked in a pre-Industrial society where people were getting more sleep overall and probably having maybe more sleep during the day and leisure time — You know, I think one of the things that that article pointed out is that even still in several other cultures it’s acceptable to take a nap during the daytime even at the office.  You know, people just put their heads down.  So it was interesting to me, but the question definitely arises of how applicable sleep patterns in pre-Industrial civilization are to our current situation now.

Dan Pardi:  Yeah, and that’s a great point.  There’s a model called the two-process sleep and wake model, and I think it’s actually really illuminating for this topic.  This was a model that was published by a researcher, Alexander Borbély, in 1983, and it is the most cited sleep article, I think, that we have today.  It’s incredibly influential in our understanding about how sleep works.  So in that model there are basically these two different processes that are influencing your levels of sleepiness or alertness at any point over a 24-hour period.  And the first process is called sleep pressure.  It’s this type of theoretical construct to explain this observation that we see in various elements of the lab.  I won’t go into that, but the idea is that sleep pressure builds from the moment you wake up.  It builds, builds, builds.  However, you don’t necessarily feel sleepier and sleepier from the moment you wake up, not at all, right?  Usually you might have a little inertia, which means you’re a little groggy for the first hour.  That’s totally normal.  Not everybody experiences that.  But then you stay somewhat stable over the course of the day.  And that’s because there is this opposing force, which is called your wake drive.  And your wake drive is basically counterbalancing this building sleep pressure.  And then in the evening the wake drive will actually dissipate.  It waxes and wanes.  It has this cyclicity.  And now all of a sudden you have this unopposed sleep pressure, and that facilitates sleep onset, and it also will help to maintain sleep maintenance if you have enough pressure.

So what happens if you take a nap during the day?  Well, you wear off some of that sleep pressure, all right?  And a lot of people, if they’re not getting enough sleep on a nightly basis, then that’s okay.  They’re actually helping to wear down some of their sleep debt, and they have really measurable performance improvements.  The other way to do that is to sleep longer at night.  But for people that are getting fully sleep satiated, if you take a nap in the afternoon, then what you’re gonna see is the sleep latency or the time to fall asleep is increased.  And then also if you wake up in the middle of the night, you might not have enough sleep pressure to maintain sleep throughout the night.  And so, that’s the model that we’re really working with, and then we have to think about how that then fits within the society.  Are we talking about if you referenced in China, India, or Spain, where they allow for naps?  You know, let’s say you become dependent on a nap, but your culture, society, or your workplace, you don’t actually get that on a regular basis, behaviorally you maybe come to expect a nap at 3 o’clock, and if you don’t get one you’re gonna practically fall asleep in your meeting.  So it kind of depends on the context of the culture that you’re in, too, whether naps are beneficial or not.

Simple tips for getting better quality sleep

Chris Kresser:  OK, this has been fascinating, and I would love to now maybe just spend a few minutes breaking this down into some tips that people can follow in terms of ensuring good sleep hygiene.  Obviously we can’t address all of the issues that can cause problems with sleep in 5 minutes, let alone a single podcast or even 10, but maybe just some general guidelines for ensuring good sleep.  You talked about the importance of getting some light exposure in the morning and throughout the day, but what are some other things that you talk about within the context of Dan’s Plan?

Dan Pardi:  Yeah, sure.  So kind of going back to operationalizing sleep, how do you then try to get the best outcome with the knowledge set?  So you believe now, OK, sleep’s important.  I want to get the best sleep that I can.  What do I do?  Well, we look at day, evening, and night as opportunities to affect this process.  And as we talked about in the beginning, timing, intensity, and duration are three of the most important things to focus on.  Most people have an idea about duration, or at least you can think about it.  So over the course of a week or two, you can think about how much sleep do I need to get for me to feel my best?  And then you can backtrack because a lot of people have fixed wakeup times either due to work schedules or school schedules, so you can then work back and say, OK, if I need 8 hours of sleep, then I know that I need to go to bed at 11 o’clock.  And what you do is you form an intention, right?  Now you have a clear, tangible time in your mind.  That’s your goal.  You want to be in bed by that time.  And that’s really important because remember, as we’re up at night, if we’ve got other sorts of stimulating influences like television, etc. — Like, let’s say if you do watch TV at night and you’re deciding on whether to watch another episode and it’s 10:45, but you want to be in bed at 11, well, if you didn’t really have a clear objective in mind, it would be very easy to just put on another show.  But if you do and you care about that, now you’re getting consistent timing because we try to gamify that.  We color-code your score around your bedtime based off of how close you are to it.  So that kind of makes it more interesting and relevant and salient.  So that’s one thing that you can do, and it actually addresses basically two out of the three:  timing, so that’s the time that you go to bed, and then the duration.

And then the third one is intensity, and that has more to do with the things we were talking about earlier.  You can’t get more sleep by squinting harder, right?  I mean, it’s not an action, but there are actions that you can do in the beginning of the day that can facilitate that.  And what we know is that sleep is dependent on the usage of our body and mind over the day.  So when you get more physical activity during the day, you will fall asleep sooner and you’ll stay asleep longer.  Light exposure first thing in the morning.  We talked about how that affects melatonin.  Of course, melatonin will influence sleep rhythms and circadian rhythms.  And I think the other thing is controlling your light environment, getting light in the morning, outdoor light several times during the day.  Try to have bright light at your office place.  And then in the evening, tone down the lights, change the tone of the lights from blue to more amber tones, and then at night try to keep your sleep environment cool, calm, quiet, and dark.  Those are the things that are gonna help to facilitate really good sleep while you’re in bed.  But you see that most of that guidance is happening outside of bed, right?

Chris Kresser:  Um-hum.

Dan Pardi:  Those are the things that you can, I think, really do to try to nurture and encourage good sleep on a daily basis.  But just prioritizing it, recognizing it’s important, forming that intention about what time to go to bed, doing some tracking, which is really simple, but then it’ll help to create mindfulness about if you’re doing it or not.  It can make a huge difference.  And we need tools that help counteract these forces and stimuli that keep us up.  So I would say count on that you do, right?  Because these things are very persuasive.  And again, it’s easiest to go to sleep when you’re sleepy, but there are reasons why we don’t necessarily feel sleepy while losing sleep.

Chris Kresser:  Well, I think that really sums up some of the best approaches you can take, and a lot of it seems to really boil down to awareness and intention.

Dan Pardi:  Yeah, forming that intention, being aware of yourself.  And I’ll share an anecdote:  There’s not a linear correlation between knowledge on a health subject and how healthy you are, right?  And just because you know a lot about something does not necessarily mean that you’re going to live that lifestyle that’s gonna facilitate that.  The professor emeritus at some university on nutrition doesn’t necessarily have the best nutrition herself.  So the point that I’m making is that a while ago, I’d been coaching and educating on sleep, and if somebody asked me how much sleep I was getting, I would’ve told them 8 hours, absolutely.  But I was tracking my sleep, and I was getting just over 7.  So I was getting basically an hour less than I thought I was.  And so that tracking can really help you understand what’s really happening versus what you think you’re doing.  And so it just makes it a lot easier to then do some course correction so that you can say, OK, you know what?  I’m not getting quite the sleep that I need, that I know that I need for me to feel my best, so let me make some adjustments.  And I think that that can keep us on track.

Chris Kresser:  And that’s, of course, equally true for physical activity, I think, which we’ll have to have you back on to talk about another time.

Dan Pardi:  All right, I’d love to.

Chris Kresser:  Well, thanks for coming on the show, Dan.  It’s been great.  I really appreciate your time, and I look forward to the next time we can have you on.

Dan Pardi:  Thanks so much, Chris.  It’s a real pleasure for me.

Chris Kresser:  So everybody, check out Dan’s Plan, again http://www.dansplan.com.  You can sign up for an account there for free and get started tracking all this stuff and set your goals for sleep and activity and weight.  And if you’re like the vast majority of my patients, it’s gonna help you a lot.  So that’s it for this week.  We’ll see you in a couple weeks.

Steve Wright:  That was a fascinating show, and I hope that everyone enjoyed it as much as I did.  And we want to thank you for listening today, and please keep sending us your questions to ChrisKresser.com using the podcast submission link.  If you enjoyed the show, please head over to iTunes and leave us a review.  It helps us with our rankings and helps the show reach more people so we can change more lives.  Thanks.  We’ll talk to you soon.

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Join the conversation

  1. Hey guys!
    Thank you for all the great info! I was just revisiting this interview, for an article I wrote on sleep deprivation, and came across the part about fasting affecting our circadian rhythm. I don’t remember hearing that before, but since I’ve been experimenting with intermittent fasting, I’ll definitely be taking that into consideration.

  2. I have taken stimulant medication in the past for ADD and notice that without the medication I am sleepy during the day – could fall asleep easily at any moment – and have terrible difficulty falling asleep at night. Once the sun goes down, my brain turns on and I just can’t fall asleep – often for hours and hours. What is the mechanism here? Is this related to a cortisol issue or gut health? I would love any advice to point me in the right direction. Thanks!

  3. I have taken stimulant medication in the past for ADHD and notice that without the medication I am sleepy during the day – could fall asleep easily at any moment – and have terrible difficulty falling asleep at night. Once the sun goes down, my brain turns on and I just can’t fall asleep – often for hours and hours. What is the mechanism here? Is this related to a cortisol issue or gut health? I would love any advice to point me in the right direction. Thanks!


  4. Hi Chris and Dan!

    I watched your (Chris’) talk on the Healthy Life Summit recently, and loved it. I’m here because I was trying to find an answer to my question:

    When getting sunlight exposure, should I take my NORMAL glasses off? I know that you shouldn’t wear sunglasses when getting exposure, as that will mitigate the positive effect of the sun’s rays, but I’m wondering if regular glasses also interfere. I’m guessing they do (sitting inside a car under direct sun isn’t the same as sitting in the direct sun).

    Let me know what you think!

    • Hi Kate,

      Minor filtering happens with normal glasses but I don’t think you need to remove them when you step outside. Better to focus on getting outside more during day and controlling light at night.


  5. So I found out lately that I have about a dozen or so SNPs that are MTHFR or MTHFR related (such as CBS, SHMT mutations). I have the hardest time going to sleep, unless I take a natural sleeping pill (some chemicals seem to work better and are better for you to have then prescription sleeping pills), I can’t seem to fall asleep. Even when I take valerian root or something else it doesn’t seem to help either. I take some supplements for adrenal fatigue (and take bone broth) i know that in the past my testosterone has been low, as my thyroid has been off too. Im not sure but its hard for me to wind down at nights and even to go to bed earlier. I believe that once my methylation gets corrected this will help out my hormones and help me fall asleep. I think I may have mismatched or off circadian rhythms though, I seem to have always been a night owl but I know in some article you said that could be do to mismatched circadian rhythms. I can’t function without a lot of sleep either, around 9-10 due to the fatigue I always feel as well from the MTHFR related health issues. Is there anything I can do to help this? I am also insulin resistant (very overweight gained back a lot of weight I had lost), and probably have adrenal fatigue to some extent as well but its mostly taken care of.

  6. Hi Dan,
    I have had a handful of kids in the last 12 years, so between being pregnant, nursing and waking when the babies/kids do in the middle of the night, I have had a difficult time trying to achieve uninterupted sleep. Now my youngest is 2, so the kids’ night wakings are rare. Since I’ve gone paleo, I have started to dream a bit and have cut my night wakings from three times to once or twice. Usually when I wake, i use the bathroom and can fall back asleep easily, but how can I get that full 7-8 hrs without waking? I can’t remember the last time I slept through the night.

    • Hi Shelly,

      My bet is that you’re waking far more than just a few times per night; probably closer to 15-20. I say this because most of us do wake up that many times, we just don’t remember those microarousals. These awakenings are not a reflection of a bad night sleep and they don’t necessarily mean you’re experiencing fragmented sleep. As we cycle between stages we also cycle in and out of brief periods of wakefulness. As we get older, we tend to remember these wake bouts more than when we are younger. These wake bouts happen when you role over and change sleeping position. It can be annoying to establish a habit of going to the bathroom during the night. If you want to limit this, watch fluid consumption before bed and then try to resist the urge (if it’s not too severe). A few nights of this and you may find you’re not having to get up to use the bathroom.

    • Hi Shelly,

      To avoid having to pee in the middle of the night, I stop drinking any fluid 3 hours before I plan to be in bed. You have to make a conscious effort to drink more throughout the day, but it works. P.S. to Dan: After having low serotonin levels on a saliva test, I’ve started supplementing with 200 mg. of 5-HTP about 2 hours before bed, and I am now able to fall asleep without a problem, even with post-hurricane Sandy worries. I am currently using 400 mg. of Magnesium Citrate, 200 mg. of 5-HTP, and 3 mg. of melatonin 2 hours before bed, and alas, my insomnia is greatly improved!!

  7. Hi Dan

    What are your thoughts on melatonin supplementation before bed-time? I know Dr. Russell Ritter recommends supplementing with melatonin for its strong anti-oxidant and anti-ageing effects. However I recall Chris Kresser mentioning somewhere that melatonin is a hormone and we should not be playing around with it.

    If you do recommend supplementation, what dosage would you recommend?
    Are you aware of any side effects on testosterone or thyroid hormone production from the use of melatonin?

    • Hi Matt,

      Before considering supplementation, it’s wise to modify behavior and environment to establish a robust melatonin rhythm. Getting bring daylight increase melatonin producing by about 50% at night. Limiting evening light and wearing orange classes can further increase melatonin production. Then, since our eyelids are translucent, limit nighttime light to a minimum (without stressing out about it).

      Supplementation may be beneficial. As Chris warns, hormones should always be used cautiously. There are very precise control mechanisms for hormones. Interestingly, exogenous melatonin doesn’t seem to alter endogenous production. You can take melatonin at various times for different reasons: 1) during the day to shift you circadian rhythm forward or backward (useful if you’re trying to adapt quickly to a new time zone); 2) after sundown to mimic a more natural melatonin rhythm in an environment with artificial light; 3) at bedtime to induce sleep.

      0.5 mg is enough to shift your circadian rhythm but larges doses are needed to induce sleepiness and even larger doses are being explored for other applications (eg, neurodegenerative disorders, cancer).

  8. Dan and Chris, I recently did a melatonin and cortisol saliva test due to sleep issues and anxiety. My melatonin levels were high- midnight melatonin was 50 pg/mL and 6am melatonin was 25 pg/mL. My 10pm cortisol was also high- 17 nmol/L ( other cortisol was in range). Any idea what those results could indicate?

    • Hi Emily,
      It’s hard to know what one measure of these hormones mean. These are moving targets. Melatonin is going to be a reflection of light and time of day as there is a circadian element to its rhythm. I would really try controlling evening light (try wearing amber classes after starting three hours from desired sleep time) and also get a lot light during the day. I would try this for a few weeks. There certainly may be other issues going on here but getting your circadian rhythms in check can only help.

  9. I can’t read the entire article and I suspect I don’t have to read it. I am not American born and I have the notion that getting enough sleep is good, not getting enough sleep is bad in my blood. Not being American born I am also familiar with such concepts as “society” or “societal problems’ and “exploitation.”
    I like this website, but I find any babbling about “sleep deprivation” without mentioning reality, such as insane workweeks (70-80 hours a week), constant American insecurity (employment at will, lack of universal health care, etc.) comical and gimmicks such as meditation techniques irritating.
    Fix this barbaric society and people won’t have a problem with sleep deprivation.

  10. Thanks, Dan! I’m 45, and maybe it’s “the Change” starting. I’m in New Jersey, but will do some research on CBT. There are some YouTube videos I found to start. I was really hoping it’s a nutrient that I’m lacking (iron is normal), or a supplement I can add that will make things go back to normal. Searching for answers is very time consuming, but I learn something new every day.

    I appreciate the input and extensive explanation!

    • Hi Cheryl,

      I battles chronic insomnia for years in grad school and it is definitely an anxiety disorder for may, though there can of course be environmental cues that make it worse (too much light at night, bad nutrition, etc). I want to share with you a tool that helped me to implement CBT in my life and helped me beat my insomnia (I had the falling asleep insomnia, but it works for both). The sleepkey is a little device that you hold while sleeping (it has as strap to keep it in place) that makes quiet beep and vibrates gently every 10 minutes or so. It sounds annoying but you get used to it. So, if you are awake and you hear it beep, you hit a button on it and if you are asleep you don’t hear it. That’s how it monitors your sleep. You spend a week training it, then it helps you implement CBT over time by telling you what time to go to bed and it tells you to get out of bed when you have been awake in bed too long.

      It is hard to go through the CBT time because you actually end up spending a lot less time in bed, which seems counter productive but it’s actually the only way to beat the bad anxiety and train yourself to sleep better.

      What I really like about it (I still use it even though my sleep is vastly improved) is that often in the morning I am actually surprised that I got more sleep than I had thought! Good luck Cheryl!

      Thanks for the episode. It’s a reminder for all those things I know I should be doing, especially because my job as a microscopist means I spend even more time in even darker conditions during the day. I try to get a few breaks outside every day, but sometimes I forget or get busy. But with my history of sleep issues I have to be very strict about my sleep. It’s annoying at times because then I can’t stay out late or it messes me up and that takes away some fun in life at times but it’s just not worth feeling awful and messing with my rhythms.

  11. I wish you would have a whole show on insomnia. I can’t fall asleep and wake around 1:00 AM very warm. I’ve been dealing with it for about 6 months now. I do absolutely EVERYTHING suggested, and have for years since learning about the importance of sleep: Black-out curtains, sleep mask, AC in bedroom set to 65, no caffeine after 12 noon, no carbs or sugar after 3 PM, exercise in the AM, good weight of 115 for 5’5″ frame-female, melatonin 1 and 1/2 hours before bed (hormone tests indicate I don’t produce much), natural progesterone (salive tests indicate very low levels at 45 yrs. old). I tested my neurotransmitters and they were found to be low in serotonin, PEA, epinephrine, & high in glycine. Used the recommended supplements from NeuroScience, and it worked for about a month, then stopped working. Cortisol levels are 7.8 ng. in AM, 2.7 mid AM, 2.5 early afternoon, and 1.5 PM. Seems a bit low according to my research about adrenals. I use adrenal support supplements: Ashwaganda, Elethero, Vit. B, C, magnesium 800 mg., plus many other vitamins & minerals. I don’t drink alcohol, nor eat processed food. No sugar. I am on Armour Thyroid. I go to bed around 8 PM because I have to get up at 4 AM. I give myself an hour to try to sleep normally, then have to take 3 mg. of Ambien to avoid becoming severely sleep deprived. No, it’s not the Ambien causing the problems. I only use it in an emergency. Progesterone & melatonin was all I ever needed in the past. Is it my adrenals? I’m sorry, I know this is a free service, and I’m lucky to even listen to your shows. I’m trying acupuncture, but it’s an expensive endeavor. There’s just no reason for me not to be able to fall asleep because I’m doing everything possible. It’s so upsetting!

    • From personal experience and other low carbers, I recommend no caffeine whatsoever – have you tried going 2 weeks without it?

      I also find (and many others agree), a carb heavy snack an hour before bed makes me sleepy. By carb heavy I mean 30-50 grams or so – this might only apply to people with low carb intakes/people in ketosis.

      My only other advice is workout (physically and mentally) as much as you can during the day.
      If you do 500 squats and 150 pushups and eat sufficient protein, I bet you will sleep like a baby.
      The same applies to spending a few hours trying to learn advanced mathematics or something.

      Hopefully Dan responds.

      • Thanks Ben. I haven’t tried going without caffeine because I feel it’s the only joy I get from not sleeping well! I know it can stay in your system for up to 14 hours, but it’s never affected me as long as I don’t drink it after 12 noon. But you may be right.

        I also do the Insanity workout, which is pretty, well, insane.

        And carbs have a tendency to keep me awake. Something like pasta, for sure, but not vegetable carbs. It may be psychosymatic, but it’s never lasted this long before. It’s like I hover right above sleep, but can’t go under.

        The acupuncture guy said the ying/yang test showed my adrenals are all low, if there is any accuracy to that. I just had my first session yesterday, and certainly did not fall asleep, and didn’t notice any difference yet.

        But thanks, Ben, for your quick response and suggestions. I’m open for any and all!

      • Hi Cheryl and Benjamin,

        Cheryl, I’m sorry about your insomnia. Let me share a story. I had lunch with Cliff Saper, who is the dean of the Harvard Neurology department, while at a conference in Ascona Switzerland. We talked insomnia. He said insomnia is really more an an anxiety disorder than a primary sleep disorder (although, undoubtedly there are different types of insomnia). Following up on this thought, I saw an excellent presentation by Prof Rachel Manber at Stanford looking at three different treatments for chronic insomnia: hypnotics (ambien), hypnotics plus cognitive behavioral therapy (CBT), and CBI alone. After 18 months, CBT was by far most effective, even compared to CBT plus hypnotics. I think you should explore a good CBT program. If you’re near Stanford, try them for sure.

        A few other thoughts: your middle of the night insomnia may not be such a bad thing, that is if you don’t worry about it too much, nor if it doesn’t significantly interfere with total sleep quantity. Our perception of how good of bad our sleep quality was, influences how we feel about our sleep, and therefore, how we feel the next day. That was the point of the Rethinking Sleep and BBC article that was briefly addressed. So, waking in the middle of the night may not be such a bad thing, but then anxiety over the waking up can keep you up longer than you normal. Again, CBT helps address the anxiety.

        Circadian alignment is critical. Get bright light exposure first thing in the morning and as Benjamin suggests, get lots of mental and physical activity during the day. A carefully controlled light rhythm (lots of outside light during the day and low light in the evening, dark room at night) should really help, insomnia or no insomnia.

        To Benjamin’s point, I don’t think you need to kill yourself with physical activity. In fact, Chris and I are talking about this on the next podcast we do together (ie, physical activity). There are a lot of misperceptions about what is needed for health and how to achieve it. I look forward to diving into that discussion. For now, yes physical activity is important for consolidated, deep sleep but you don’t need to do 500 squats to ensure the benefit happens.

        Also, Cheryl, I’m not sure how old you are but during menopause, there is a loss of a gaba-active metabolite of progesterone. This leads to increased anxiety and insomnia for women going through this life change. I wish I had a quick fix to share but I would just go back to the default guidance on health sleep and explore CBT too.

        Hope this helps!

        • One more thing. Yes, carbs can make us sleepy. While this is generally appreciated by folks who experience the effect, generally the description of why this happens is inaccurate. Blood sugars can be sensed by the brain. Glucose will inhibit the primary wake system in the brain that is located in the lateral hypothalamus and perifornical hypothalamus. At the same time, it will increase activity in an area of the brain that is primarily responsible for initiating sleep onset and maintenance – called the ventral lateral preoptic area (VLPO). This is the part of the brain that increases in activity upon sleep to directly inhibit other parts of the wake network. As you could image, both actions will make you more sleepy. Hope this wasn’t too nerdy:)

          • Yeah fair enough regarding the squats. I suppose intense workouts to get into sleep is more of a symptom treater. I don’t think high volume training is bad though, provided you eat enough keep it resistance oriented. Things like sufficient dietary fat, protein, antioxidants, etc are all helpful for recovering.

            Interesting about the glucose and sleep. All I was told was it had to do with insulin haha. I usually eat a banana before bed.

            Could magnesium be a factor? that also knocks me out when I take it.

            Regarding anxiety, certain types of meditation address this. I believe mindfulness meditation is fairly effective. Tons of studies out there, and you only have to do 20 minutes a day or every other day or something. Unless that’s what Dan is already referring to, in which case sorry for being redundant. I certainly do recommend meditation though – clears head, increases focus, decreases anxiety and depression.

  12. Can getting up early (~4:30am) to exercise disrupt normal diurnal sleep and hormone cycles and lead to chronic sleep problems , even if you get to bed early (8:30-9:00pm)? Does the type of exercise make a difference? Thank you

    • Sage, if you maintain that daily rhythm – and don’t vacillate sleep and wake times on a daily basis, and have adequate sleep duration – I don’t see cause to worry about this type of schedule.

  13. In this day of flourescent lights, where does one find amber lighting?

    Also, is anyone looking into how diet (apart from caffeine or alcohol) affects sleep? Eg, I find it much harder to go to sleep if I have corn syrup during the day. I would like know if there are any studies looking at other types of foods and how they impact sleep.

  14. This is highly significant in light of a recent cross sectional study demonstrating that nearly one-third of US adults get less than 6 hours of sleep per 24 hour period.

  15. @Rodney, the black quiet room is the optimal sleeping environment.

    great address, sleeping is a crucial and important aspect of our happiness in this life. Sadly the chronic sleep disorders is a real epidemic in the world today and more knowledge on the subject needs to be addressed. Interesting how you realized that you were getting an hour less than you thought. It makes me want to record a sleep journal just to know how many hours I can get in a week.

    • Hi Allison,

      Tracking has been one of the best things for my sleep. I would guess I average about 30 minutes more sleep since tracking because it keeps me mindful of my sleep time on a daily basis. I also feel confident saying that since doing this, I have really noticed a difference in my daytime performance. I was already a believer in the importance of sleep, now I just have a more stable daily sleep practice.

  16. How does the fact that co-sleeping with a nursing child for multiple years has been the norm throughout history fit into this? It’s easy to say that co-sleeping means that the mother’s sleep isn’t disrupted as she nurses while co-sleeping, but I’m only one of many, many, many moms who will say otherwise. It is disrupted – it’s just not *nearly* as disrupted as it would be if the baby were sleeping elsewhere and still needed to nurse. (Not to mention the squirming, poking, kicks to the chin, etc.) The average American doctor will say that the solution is to night-wean and sleep train – voila! Mom can once again sleep for an uninterrupted eight straight hours, as nature intended…..really?

    • That’s a great question, and one I can definitely relate to at this point in time, since my wife and I co-sleep with our 14-month old daughter. I’d like to hear Dan’s opinion on this, but I suspect that some of the hormonal changes that occur during lactation may help mitigate or attenuate the effects of sleep-deprivation in nursing women. This is a purely anecdotal theory based on the observation that I seem far more affected by the sleep disruption than my wife!

      • At this point in my life, I have not explored different solutions or techniques to sleep in regards to young children. However, some fundamental sleep principles remain. All parents have their sleep disrupted to some degree with young children. This fragmentation is likely fine if two conditions are maintained:

        1) circadian desynchronization is minimized. Limit light during nighttime feedings. If you need to have a light on, get a amber light bulb on a dimmer switch. This will benefit all involved.

        2) sufficient total sleep time is accomplished in a 24 hour period. Daytime naps are impractical for many parents (due to job), and so the reduce sleep time and quality at night is not accommodated for by daytime naps. This leads to a sleep deficiency, with impairments in mood, decision making, vigilance, physical vitality, etc. Co-sleeping presents a bigger risk for disrupted sleep for the parents. If this is what you choose to do, and you cannot get sleep during the day because of your work, schedule time for naps on the weekend to wear off sleep pressure. The best opportunity to nap – from a circadian perspective – happens during the afternoon between about 2-4p. This is when many cultures nap because there is a natural dip your wake drive, so if you’re carrying sufficient sleep pressure, sleep will easily take place at this time of day. Even if you’re tired, you may not be able to sleep at other times during the day because your wake drive is active. However, this is entirely dependent on how much sleep pressure you’re carrying. If you’re carrying enough, you’ll be able to sleep at any point in a 24 hour period.

        Lastly, I would say that if you are co-sleeping but your sleep is really disrupted and you’re miserable, you should consider not co-sleeping. Good parenting requires that you be present, alert, and mentally stable at other points in the day so be realistic about what is working. The best solution for you family may not be co-sleeping but if you want to try it, start there and see if you can make it work using some of the napping and lights solutions I mentioned earlier in this response.

        • it’s interesting that the best opportunity to nap is supposed to be between 2-4pm. that is when I often sleep the best – most soundly. can you provide a reference on that? Thank you. Great Podcast. Kindest Regards.

          • LJ, check out principles and practice of sleep medicine. It the standard text book for sleep science. We’ve know of this circadian dip for a long time but I don’t know who first identified it. In fact, all sleep text books will discuss this. Also, check our work from Chuck Czeisler at Harvard, the foremost circadian biologist in the world. Chuck’s work has explored these topics from every sort of angle. Cheers

  17. Great podcast! I have two questions.
    1. Do we need a pitch black room to sleep in, meaning ANY light source (nightlight, clock, filtered light through windows etc) has a negative effect on sleep? Or, is it just a matter of MINIMIZING the light sources?

    2. Are the orange colored glasses that filter blue light of any benefit in the evening after sunset, or are we better off just trying to turn off tv and computers an hour or so before bedtime, and keeping light intensity as low as possible with dimmers etc.?

    • Yeah I was interested in the sunglasses thing too. I have some “Blublockers-” they’re great in really bright sunlight, but I’m wondering if the blue light from the sun is actually beneficial, and use of sunglasses could be somewhat limiting (think: sunscreen)… Obviously too much can lead to sunburn/Photokeratitis, but the right amount of UV radiation contributes to vitamin D production: Is this comparable to the eye? I would be interested in hearing if the UV-filtered sunlight one receives with sunglasses would have the same effect on the circadian rhythms that Dan was talking about.

    • Hello Rodney and Wade,

      Glad you liked the podcast. Good questions.

      Room light at night: Let’s address this question by first considering pitch black room (zero light). I don’t think there is any issue with complete darkness and we may consider it amongst the best options. However, there is a caveat to this: You must also make it a habit of getting outside light as soon as you wake up or your will be at risk of having your rhythm delay (wake up later, go to bed later) Now, how much light can we have in a room before we start to experience suppression of melatonin and shifting of circadian rhythms? Don’t know. There is always individual variability and there is even going to be variability in the different light receptors in the eye. I spoke mostly of the retinopsin producing intrinsically photosensitive retinal ganglion cells in the eye that perceive light and influence circadian rhythms but there are other ganglionic cells that are light sensitive (different classes) that likely influence this system – basically, any light that enters the eye has the ability to influence the system, regardless of spectrum (ie color). Having said that, we did not evolve sleeping in a zero-light environment. I suspect that we can have zero negative health impact with some light in your sleeping environment. But, we are also no longer living in a natural light environment. Probably 99.9% of us now have artificial light in the evening so our total darkness period is truncated. Additionally, there is less seasonal variability of this darkness rhythm and I don’t know if anyone has researched the effects of this questions. In the absence of complete information on the subject, we aim to make informed choices and I’ll tell you what I personally do. I make my room very dark without worrying about some light in the room. I also get outside FIRST THING when I wake up to get intense light into my eye. By the way, I do have clocks in my room. They emit red light and I turn down their brightness to minimum intensity.

      To address your second question, the orange glasses are a bandaid to the reality of our modern world. They help us do better. What we don’t want to do (I think) is experiment with an extreme solution for two weeks and then give it up completely because it’s just not practical or sustainable. I use orange glasses but I’m most diligent about this when I read my ipad in bed (not too frequently). I would NOT wear blueblockers during the day. Ever. My normal (not orange) sunglasses have a light shade and I mostly use them when I drive for safety (or simply to look really really cool in my honda civic). Remember, getting intense light during the day increases melatonin secretion at night. Let’s review what matters with light for both affecting melatonin and circadian rhythms: light intensity, spectrum, duration of exposure, maybe the UV aspect of light, and of course timing (when the light occurs).

      Get bright, outdoor light during the day. Take measures to limit light in the evening and night. Make these solutions practical in your life so they are sustainable.

      • Thanks for the thorough reply Dan! I have tried the orange glasses, but don’t enjoy wearing them and so find my use irregular at best. I do have f.lux on my computer which helps some as I understand, but don’t have a similar option for nighttime tv. I also keep my lights dimmed after dark, so other than the tv issue I think I am doing fine!

        • Hi Rodney,

          Let’s make a deal and both try to wear the orange glasses while watching TV. We can do it!

          Otherwise, sounds like you’re doing well with all this. Kudos!

      • So just to clarify- orange sunglasses such as Blublockers, should only be used at night for dealing with blue light? What is the main reasoning behind your recommendation for not wearing them during the daytime? I guess I’m just a bit confused… (Aren’t “spectrum” and “the UV aspect” the same?)

        Should any sunglasses be used during the day?

        Thank you for your help Dan! Love your website btw.

        • Wade, yep. No blue blockers during the day because they filter blue light and we want that during daylight hours. So UV light is light radiation that is not visible to humans (but is visible to some animals and insects) and blue light is a (obviously) visible light that has uniquely potent properties to influence our circadian rhythms. However, UV light may influence circadian rhythms too. I wear glasses sometimes during the day but I try to go without mostly.

          So glad you like the website, Wade. Working hard on it.

          • Ok got it. Blue light is visible, but not has not yet entered UV wavelengths. The blue/violet ends of the spectrum (may) influence the circadian rhythms. Thank you for the recommendation too- I’ll be weening myself off of sunglasses ;). Once again, great info here, and thanks for coming on the podcast!

            • Hi Wade, one adjustment.
              UV light may influence circadian rhythms, blue light definitely does. You’re welcome, it was my please. Glad you got something from it!

  18. At age 71, I have absolutely no problem falling asleep, but I awake too early (about 5.5 hours). A sleep mask has no effect. A lot of physical exercise makes me awake even earlier! I am otherwise fairly healthy and do not feel tired during the day unless I spend too much time in a recliner.

    I think my problem is called terminal insomnia, but beyond that I can find little information. Any ideas?

    • Yes. Get your cortisol and DHEA levels tested with a saliva hormone profile from BioHealth Lab. Early morning awakenings like this are a classic sign of cortisol dysregulation.

    • Waking up early – or earlier than typical – isn’t necessarily bad. Shorter sleep without untoward side effects is not necessarily insomnia. This might not be something you need to worry about. Also, as we age, many of us experience a shift in our circadian cycle such that we go to bed and wake up earlier. Some of this has to do with how our eyes change in sensitivity to light as we age. If you would prefer to delay your rhythm (go to sleep later and wake up later than you are now) avoid intense morning light, food and physical activity until about 8 am and get brighter blue light and physical activity in the evening. This can push your rhythm to a later time. Try it for about 10 days for the effect to settle.