I somehow managed to get on the press list of the Annals of Internal Medicine. That means they send me embargoed papers before they're released to the general public. That journal publishes a lot of high-impact diet studies, so it's a great privilege for me. I get to write about the studies, and publish my analysis at the time of general release, which is the same time the news outlets publish their stories.
One of the papers they sent me recently is a fat loss trial with an interesting twist (1; see below). All participants were told to eat 10% fewer calories that usual for two weeks, however half of them were instructed to sleep for 8 and a half hours per night, and the other half were instructed to sleep for 5 and a half hours*. The actual recorded sleep times were 7:25 and 5:14, respectively.
Weight loss by calorie restriction causes a reduction of both fat and lean mass, which is what the investigators observed. Both groups lost the same amount of weight. However, 80% of the weight was lost as fat in the high-sleep group (2.4/3.0 kg lost as fat), while only 48% of it was lost as fat in the low-sleep group (1.4/2.9 kg lost as fat). Basically, the sleep-deprived group lost as much lean mass as they did fat mass, which is not good!
There are many observational studies showing associations between insufficient sleep, obesity and diabetes. However, I think studies like that are particularly vulnerable to confounding variables, so I've never known quite what to make of them. Furthermore, they often show that long sleep duration associates with poor health as well, which I find highly unlikely to reflect cause and effect. I discussed one of those studies in a post a couple of years ago (2). That's why I appreciate this controlled trial so much.
Another sleep restriction trial published in the Lancet in 1999 showed that restricting healthy young men to four hours of sleep per night caused them to temporarily develop glucose intolerance, or pre-diabetes (3).
Furthermore, their daily rhythm of the hormone cortisol became abnormal. Rather than the normal pattern of a peak in the morning and a dip in the evening, sleep deprivation blunted their morning cortisol level and enhanced it in the evening. Cortisol is a stress hormone, among other things, and its fluctuations may contribute to our ability to feel awake in the morning and ready for bed at night.
The term "adrenal fatigue", which refers to the aforementioned disturbance in cortisol rhythm, is characterized by general fatigue, difficulty waking up in the morning, and difficulty going to sleep at night. It's a term that's commonly used by alternative medical practitioners but not generally accepted by mainstream medicine, possibly because it's difficult to demonstrate and the symptoms are fairly general. Robb Wolf talks about it in his book The Paleo Solution.
The investigators concluded:
Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal ageing and, therefore, sleep debt may increase the severity of age-related chronic disorders.So there you have it. Besides making us miserable, lack of sleep appears to predispose to obesity and diabetes, and probably sets us up for the Big Sleep down the line. I can't say I'm surprised, given how awful I feel after even one night of six hour sleep. I feel best after 9 hours, and I probably average about 8.5. Does it cut into my free time? Sure. But it's worth it to me, because it allows me to enjoy my day much more.
Keep your room as dark as possible during sleep. It also helps to avoid bright light, particularly in the blue spectrum, before bed (4). "Soft white" bulbs are preferable to full spectrum in the evening. If you need to use your computer, dim the monitor and adjust it to favor warm over cool colors. For people who sleep poorly due to anxiety, meditation before bed can be highly effective. I posted a tutorial here.
1. Nedeltcheva, AV et al. "Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity." Annals of Internal Medicine. 2010. Advanced publication.
* The study was a randomized crossover design with a 3 month washout period, which I consider a rigorous design. I think the study overall was very clever. The investigators used calorie restriction to cause rapid changes in body composition so that they could see differences on a reasonable timescale, rather than trying to deprive people of sleep for months and look for more gradual body fat changes without dietary changes. The latter experiment would have been more interesting, but potentially impractical and unethical.
I myself have gotten into the habit of dimming all lights in my house after sundown. Even though working in he computer industry often causes me to be up fairly late working in front of a computer screen, I have found a handy util to blunt the impact of that as well, it is called f.lux:
Essentially dial in your geographic location on earth, and it will dim/redden your computer screen as the sun goes down! The difference is amazing.
I have also started using a clock WITHOUT light-up LEDS, and putting black electrical tape on all the LEDs and light sources in my room. I've also gotten some 'black out' curtains for the windows in my room.
The difference has been absolutely nothing short of staggering in my life.
A very timely post & study Stephan! I have just returned from presenting a workshop on sleep in Auckland. I am a nutritionist by trade but I present on sleep more than any other topic that our corporate clients self-select - sleep debt just seems to be such a huge issue for most.
The problems with carbohydrate metabolism and sleep is a bit of a chicken and egg scenario and puts people into a viscious cycle.
Like you, I am a 9 hour (6 sleep cycle) sleeper to feel fully refreshed (though I admit this blogging game sometimes eats into that). I can tell you that switching to a high fat paleo-type eating platform, engaging in heavy lifting and sprinting late in the day, and a good dose of magnesium pre-bed sees me sleep with the dead most nights (allowing for the occasional 4.5 - 7.1 magnitude earthquake waking me up).
Appreciate all your work Stephan!
This is interesting: serotonin antagonist increases slow-wave/deep sleep...
...Does the "sleep" inducing effect of insulin + tryptophan lead to more, yet lower quality sleep?
Interesting difference, but they must've eaten a lot less than just -10%. 2.4 kg pure body fat in 2 weeks is like a 1300 kcal deficit per day.
I feel best after 9 hours, and I probably average about 8.5. Does it cut into my free time? Sure.
If I slept 9 hrs. a night I would have to abandon all my non-work activities (including parenting)
I don't know if the trial is controlled enough for me. Because sleep is a low metabolic state, the group which sleeps less is going to have a greater energy deficit to make up.
This means that another valid interpretation is that when the energy deficit crosses a threshold the body decides to start burning muscle.
Another problem is just that the 5 hour group had to undergo a more severe stress. It is possible that if they gradually went down to 5 hours so that they could get used to it that the results would be different. That would also help with the previous mentioned problem- get them down to a normal 5 hours first, then have them drop 10% of calories.
I would also want to see if the groups were equally lean and if napping was controlled.
I am not saying your interpretation isn't correct, it just seems like we need more (different) studies to be able to have confidence in it.
I consider getting enough sleep to be one of the most important factors in my own health's recovery (the other being diet). A good diet and good sleep go hand in hand. It's hard to have one without the other.
i do best on 10 hours but i never get it. it REALLY makes a difference in my digestion and ability to handle carbs well
between sleep and sun exposure i dont know which impacts me more. both are more important than what i eat
I think sleep is huge. I can't recall where, but it sticks in my mind that the brain burns quite a lot of energy during sleep whereas, the rest of the body is at rest - and that doesn't even take in into effect the psychological factors.
When I was a fat bastard, I used to pride myself on 5 hrs of sleep. Now I average about 8, shamelessly.
@Richard, since when did the word "fat" come before that descriptor? :-) Sorry, couldn't resist.
Good stuff Stephan and props for the recognition.
One of my favorite books is Lights Out: Sleep, Sugar and Survival by TS Wiley. Published in 1999, if I recall. Some over the top stuff, for sure, but a good read overall.
I was reminded of a quote from the book when you said, does it cut into your free time. In the book they basically asked the same question, but answered it by saying, death screws up your free time too.
Could it also be circadian rhythms? I sleep 7.5 hours a night but it's not so much the hours as when I go to sleep. Going to bed early and waking up after 7.5 hours isn't nearly as good for me as going to bed at my usual time and getting the same amount of sleep.
I noticed that when i switch the lights off I tend to "wake" up and have a harder time getting to sleep. I need to have the lights on otherwise it disrupts my sleep
Btw, You may find these things interesting:
It's quite interesting that some people get acne-free by fixing their circadian clock by being the days in very bright light (outdoors with no any glasses or in front of extremely bright lamps) and nights in very dark room.
Sweet! I'm now going to factor sleep into my diet plan EVERY day! =)
Hi Stephan, Yes, just as food, sunshine and exercise, sleep is an important part of the "package". My personal experience is that I started to sleep more hours per night as soon as I started a paleo low carb sort of diet. With or without lights on, round 10pm I feel the Sandman sprinkling sand onto the eyes.
thanks Stephan =)
I have a thought, that maybe we should eat more nutritional dense food but in smaller amount,so the body can use the energy on other activities rather than digesting.. so we are less fatigue and can have qualitative sleep but not as long?
what do you think?
While shift work is far from ideal in an evolutionary sense, do you think it would take as much of a toll on a person who still manages an average of 8 hours or more of sleep per day, or is this still as, or almost as, deleterious as receiving too little sleep on a regular basis?
As far as your comment about light in the blue portion of the spectrum, would there be any benefit to wearing "blue blocker" sunglasses in the evening while at home? Could this potentially impact upon melatonin secretion? Or perhaps that is just my unscientific mind at work on that one and jumping to overly simplistic conclusions.
Being a shift worker myself I can say that sleep is the most important thing in anyone's lifestyle. even more so than diet.
The research on light/dark doesnt seem to have an affect on me, my circadian rythm seems to be highly tuned to some kind of invisible clock that is not effected by light, although I find it hard to get to sleep in a well lit room, aslong as the room is dark when I actually get into bed it doesnt matter what kind of light I was exposed to beforehand.
Having said that different things seem to affect how the circadian ryhtm advances and delays.
I expect that abnormal light exposure from modern living has cumlative effects on delaying peoples circadian rythm's which can help explain why people sleep badly.
I've noticed that, going to bed and trying to force yourself to sleep before your actually tired enough to sleep is extremely bad and results in tossing and turning all night and getting extremely bad sleep that night overall. Whats happened here is the circadian rythm is delayed. And going to bed too early further delays it.
Ive had success with afternoon melatonin supplementation for advancing the circadian rythm, its more effective than taking any 'bedtime' supplementation.
peter-fonzanoon, being a shift worker myself I would say that it wont matter aslong as you feel good and refreshed after the sleep and your diet is in check. The longterm effects on your health will be minimal.
The problem I had with my shift work is I never got 8 hours after a nightshift, always woke up after 5. If you can get the 8-9 hours everytime you go to sleep and wake up feeling refreshed then thats all you need to worry about.
Thanks a lot, Stephan.
In addition to how long we should sleep, an interesting question is in what cycle.
Jessa Gamble recently gave a TED talk on what our evolutionary sleep cycle might've been. She found that it might not be a straight 8 hours. Rather, it might be 4 hours of sleep, followed by 2 hours of meditative/half-sleep, followed by 4 hours of sleep.
Very, very interesting!
Thank's a lot for this article, Stephan!
Good article, Stephen.
There is certainly an increasing amount of controlled studies showing how sleep deprivation disrupts metabolism and appetite regulation. I covered one study showing how subjects ate more when sleep deprived:
Nice article ! I wonder if the results were in favor of longer sleeping hours because of the possibility of the these subjects being in fasting state for that long. It would be interesting to see if the paper mentions whether the individuals who had ~4 hours of sleep had their first meal immediately after waking up.
I've heard of other studies that mention 7 hours as the magic number. I more curious about which method to increase sleep is best, going to bed early vs sleeping in? My guess, sleeping in does very little to make up for sleep debt.
If adrenal fatigue produces "general" symptoms that are possibility correlated with a range of other factors, how does one determine that this fatigue exists at all? More importantly, how does one treat something so elusive?
I've heard this idea pop up amongst alternative practitioners, but everything I've heard suggests to me that there is an unclear idea of causality. Is some deficiency "causing" adrenal fatigue, or is it a vicious cycle of stress and sleeplessness?
Stephan, I'd like to know more of your thoughts on this subject as it's difficult to find fully trustworthy resources on adrenal "dysfunction."
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Krieger and Guynet; I've always felt like my hunger signals get all screwed up when I seel very little, usually less then 6 hours..
I think that advice about blue light may be generally correct, but not universally. I have been affected by SAD in the past, which also affects sleep. I purchased one of those blue SAD light units, and as part of the purchase, they provided a questionnaire about sleep habits and energy levels. Based on my responses, it was suggested that I use the light in the evening about 60 minutes before bed time and not in the morning. When I did that, I found my sleep was deeper and it eliminated my tendency to wake up at 4:00 am or so and have trouble getting back to sleep.
Hi Stephan...haven't commented in a long time but still a regular reader.
First, let me say that I have taken all of this advise about sleep very seriously over time and have a completely darkened room, etc. But...
What is the evolutionary case for absolute darkness? Man never slept by campfires, or under the stars? Talk about a million white LED lights "disturbing" your sleep...sleeping outside on a mountain under a clear sky blows away a few alarm clock lights.
And the bright, full moon has been rising during sleep time for quite awhile.
Anyway, I love the totally dark room but I'm not completely convinced that our ancestors always slept in the very back of the cave.
Have you seen this article, with journal links, on how many different processes insulin signaling controls? "Several groups of scientists are finding clues that suggest many major illnesses result from disruptions to one complex molecular cascade—insulin signaling."
I've been wondering about the extraneous sources of nighttime lights, too, esp the occasional nights with bright full moonlight that sometimes awakens me. I find the theories that a sleep/brief wakening/sleep cycle was more common prior to electricity very interesting and quite plausible based on my great grandmother's rural life (1895-1980) and her sleep comments. She retired to sleep only about an hour after dark.
I know I need to do a better job of retiring earlier in the night and fighting the second wind I often get in the evening; it's a work in progress not made any easier by the hormonal shifts of perimenopause. As I get older I notice I am much more sensitive to shifts in daytime and seasonal light cycles (for instance, my thyroid hormone dose needs to be shifted up a bit right about now, and shifts down again in the spring). I try to make a point of getting outside into some bright sunlight midday, too.
While I do turn my clock display away from me and keep interior light sources off or to a minimum, I am still reluctant to block out all natural exterior light sources, esp with room darkening shades. The only time I sleep with darkening shades is when traveling and staying in motels where people can pass by the windows - otherwise I always keep some of the drapes back with sheer curtains across the windows so the sun can gradually wake me.
Dark rooms do allow for longer & deeper sleep, but I really don't like the feeling I have when I wake up in a really dark, gloomy, cavelike room; even after a decent night's sleep I wake up abruptly feeling groggy and disoriented.
Anna, regarding your comment on the brief sleep/wake cycle...I read a book on bushmen once that mentioned there was always someone awake at night. They naturally rotated through this role throughout the night, watching the fire, watching for lions, etc. for an hour or two then went back to sleep while another took over.
I recommended the work of Raymond Chandler to a colleague just this afternoon.
That said, I should really get to sleep, but not in the sense that Chandler meant...
very important post. I can add (to all what you wrote) that it seems like lack of sleep also impacts hunger regulation mechanism as well as immune system.
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I wanted to ask about the potential benefit of napping. Many have suggested that a 20-30 minute mid-day nap is worth several times its weight in night-time sleep.
Do you have any thoughts about the efficacy of taking a nap ?
Interesting article! My problem is that my body will not let me sleep more than 6 hours. I am 49 years old, and have always been this way.
I go to bed at 11pm and get up at 5am for work. If I went to bed, say, at 10pm, then I would wake up around 4am. It's just physically impossible for me to sleep more.
On the very very rare occasions if I do sleep longer, I wake up with a screaming backache.
My friend accidently jumped on my foot. After two weeks, its not feeling any less painful.when i step on it a certain way it hurts really bad. What should i do? <a href ="http://www.1lig.net>health advisor</a> I dont want to get x-rays unless we need to?
Just a few questions! What method was used to determine body composition?
I read the abstract on pubmed and the numbers they list for fat loss/weight loss is 0.6kg/3.0kg for the 5.5hour and 1.4kg/2.9kg for the 8.5hour! Did one of us misinterpret the numbers?
Whoa, I did read that wrong! The low-sleep group barely lost any fat at all, but lost quite a bit of lean mass! Thanks for pointing that out, I'll have to publish a little correction.
On the other hand, I saw a report recently of findings on sleep and longevity which indicated that, in a particular group studied, people who got less than 5 hours or more than 6.5 had significantly shorter lives. In this group, 5 to 6.5 hours was the sweet spot for longevity. I think it was an observational study, and was from someone named Kripke in San Diego. Don't know what to make of it, but thought it was worth mentioning.
A few months ago, I had taken to wearing some amber safety glasses in the evening, that block all the blue light that would otherwise stimulate the recently discovered retinal ganglion cells in the eye. When blue light stimulates those ganglia, melatonin release is suppressed. Supposedly, even if paleo man stayed up late around the fire, it was all orange, yellow, and red light, and did not stimulate those ganglia, so melatonin would flow. What I noticed, though, was that when I had worn those glasses for a couple of hours before bed, I would wake up way earlier. Like around 3 or 4! It was n=1 with no control, but still interesting (at least to me!).
Here is my contribution to you all: A weblink.
This software was written by the guy who wrote Picasa. It is far, far better.
You'll sleep better and your life will be that much better if you install this teeny tiny little thing. (No, it isn't a scam or a virus. You can search for f.lux on Mark Sisson's site if you don't believe me. What it is is my favourite software to lower the color temperature of your monitors at night so the blue light doesn't mess with your melatonin and your circadian rhythms).
f.lux -- by the creator of Picasa
I should read before I post!
The very first comment here is someone recommending the same program.
Well, Skorz is bang-on. Get it! Works on Mac, Linux, or PC.
Christoph, you couldn't have made it sound more like a virus if you had tried, haha. I'm with you though-- it's a good program. I have it on my laptop.
I have found some herbs of assistance in promoting sleep.
Chaste tree AKA Agnus castus has been found to increase melatonin production.
Exp Clin Endocrinol Diabetes. 2003 Feb;111(1):44-6.
I have read that kava kava is a melatonin catalyst but haven't found any scientific literature on this. Personally, I have found it helpful for promoting good sleep.
This was a great article on sleep. I am an insomniac - I have tried everything, finally resorting to prescribed medication which I need at least every third night or I'd go insane. How does one "shut down" the mind to go to sleep? I have yet to find an answer.
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Thanks Stephan for great post! I really like it!
strange most everyone gets a better sleep after switching to paleo diet.
my sleep problem just gets worse on hyperlipid diet cause i have more energy; so i just don't get sleepy until almost 0200. (i do stop having caffein after about 1730)
f.lux does not seem to help me.
i need about 8 hr sleep. but on weekdays, i only get 6-7 hrs. :-( so i sleep 10-12 hr on weekends.
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Is there a possibility (or was it controlled for?) that the group with lesser sleep simply exercised less during the day, thus lost more muscle mass, as opposed to the well-rested group with probably more energy to be active, thus maintained their muscle mass?
Regarding one poster's comment on his use of melatonin during daytime, studies show that this practice may lead to eye damage (review http://www.supplements-and-health.com/tryptophan-side-effects.html ) -but the longterm (artificial) increase of the substance along with tryptophan and serotonin may not advisable anyway because these substances have been linked to brain degeneration, inflammation, free radical production, metabolic disruption, fibrosis, hypertension, higher mortality, cancer, and so on (see previous link).
Finally! A question on my mind that has been bugging me for quite some time has been answered!
I was wondering why I am getting a bit fatter when I go on graveyard shift at work. Then I realized I was only having around 4 hours of sleep when I'm on night shift! Hence the explanation on your article!
By the way it would be a huge honor if you pay a visit on my health website that I've been recently working on. It's called The Healthy Happy Life. And maybe someday I can ask for a guest post from you. I would highly appreciate it.
I notice that I lose weight by a few hundred grams each night that I have a good sleep ie, in bed and lights out at 10:30. Oddly, on these occasions, I end up waking up at around 5 am and I just lounge around until 7. Knowing that the weight loss occurs should be enough for me to just go to bed early every night, like I did 30 years ago, but the late night addiction to the internet sets in and I find myself turning off the lights at past 11 pm.
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