Bedtime Honey and Sleep: More Evidence It Works

In a 2010 forum discussion I found this:

SLEEPY HEAD I read that honey helps you sleep. I’ve tried it the past few night and have slept very well! I have had trouble falling asleep and staying asleep since I was born. I even take Ambien sometimes and still stay awake alllllll night long. I can’t believe how well I slept the past 2 nights. Just take one teaspoon of honey before bedtime and sleep like a puppy!

USER 967048 I took honey again last night and slept awesome. I have found that 2 tablespoons work the best.

USER 968407 I took honey again last night and slept like a baby again! This really works!

USER 602568 I’ve been sipping a cup of milk with a couple teaspoons of honey on nights I can’t sleep. It always works. But I thought it was the warm milk. I didn’t realize the honey was the key ingredient.

More evidence that as little as one teaspoon produces a big improvement. One teaspoon of a common food can greatly improve something as important as sleep!

 

Bedtime Honey: Other Benefits Besides Sleep and Strength?

After I’d been taking bedtime honey for 3-4 weeks, I began to notice changes in addition to better sleep and more strength. One was a sense of increased well-being throughout the day. Not better mood, not more energy, just somehow better. Another was better motivation. It was easier to do everything — pushups, putting stuff away, and so on. My life was not perfectly constant, however, so I could not be sure these changes were due to the honey.

I asked Jason DeFillippo of Grumpy Old Geeks about this. Bedtime honey really helped him. He replied:

I have noticed that during the day I can concentrate for much longer stretches but I was chalking that up to the sleep. I think the motivation you’re talking about is definitely starting to manifest itself quite a bit more as well. I’m putting more effort into my business than I have since I started it 2 years ago and haven’t really thought about it being a side effect of the honey but it’s possible. Amazing things happen when you haven’t slept properly for 20 years and can now sleep through the entire night.

After he mentioned concentration, I realized I had noticed the same thing: I could do work that required concentration for longer periods of time. In contrast to Jason, I had slept well for many years before starting the honey — or so I’d thought.

Bedtime Honey: Less Honey May Be Better

Some people find that bedtime honey does not work, at least initially. One reader wrote:

I tried it out for several days now [1 tablespoon of honey], and it produces in me a similar effect as when I go to sleep when I have drunk several beers before. I wake up several times during the night, vivid dreams, and feel less rested in the morning rather than more.

I suggested a smaller dose — 1 teaspoon, which may be effective. He tried it:

I have taken a teaspoon of honey now for three days and my experience so far is that it is better than a tablespoon of honey. I vaguely remember that I dreamed but do not remember about what. Today I also noticed that reading in the train was easier than before, despite waking up earlier, I felt I understood and retained more of what I was reading. What I find most surprising over these three days is that I don’t use my glasses as often as before.

So if a tablespoon causes you to wake up in the middle of the night, try a smaller dose. I haven’t yet tried a range of doses.

Sleep: Summary of What I’ve Learned

I want to summarize what I’ve learned about how to sleep well. I’ve found about a dozen changes that helped. Taken together they suggest the importance of four dimensions:

1. Healthy brain. My sleep greatly improved when I ate a lot of pork fat. (As far as I can tell, butter produced the same effect.) I wasn’t getting enough animal fat. My sleep also improved when I started eating honey at bedtime. I assume honey raised blood sugar to better levels during sleep, improving brain performance. The great importance of this, I believe, is why we evolved preferences that push us to eat strongly sweet foods, such as fruit, separately and later, i.e., dessert. Bedtime honey also caused my muscles to grow more in response to exercise — a sign of better sleep, since muscles grow during sleep. I have never measured the effect of flaxseed/flaxseed oil on my sleep but the brain benefit was so clear in other ways I’d be surprised if it didn’t improve sleep. Continue reading “Sleep: Summary of What I’ve Learned”

Why Does Bedtime Honey Improve Sleep? More Helpful Data

At Free The Animal, Richard Nikoley blogged about the value of potato starch and other examples of resistant starch (RS) which is slowly-digested starch. As a reader of this blog named Xav points out, three commenters say it has improved their sleep:

1. On week three of 3 TBS of Potato Starch per evening. Any explanation on the exceptional, uninterrupted deep sleep? No complaints mind you. Have never slept so well. Never. [Richard did explain the deep sleep — Seth]

2. After a few days of a few Tbsp RS in the evening, here are my observations . . .

  • sleep has been better the last 2 nights without any particular change of lifestyle.
  • dreams are vivid, I remember them much more

3. I took 4 tbsp of PS last night. . . .I had an incredible sleep (but no vivid dreaming, however). I mean, I did not wake up even once. I was sound asleep from the beginning to the end and it was such the most sweet and tranquil sleep I ever had in a long time!

Emphasis added. Someone else said, “Have been doing this for about a week now. 2T in am and 2 T after dinner. Sleep may be better.” No one reported better sleep after resistant starch at other times. Richard said nothing about the time of day to eat it. Several people say it raised their blood sugar.

Readers of this blog know there is abundant evidence that bedtime honey improves sleep. Honey is not a resistant starch, although fructose (honey is half glucose, half fructose) is digested relatively slowly. Potato starch and honey differ in many ways. That both, eaten near bedtime, produce better sleep, suggests that the better sleep is due to something they share. One thing they share is both increase blood glucose throughout the night. Honey does so because it contains a quickly-digested sugar (glucose) and a slowly-digesting one (fructose). Potato starch does so because its carbohydrate is slowly converted to blood glucose.

The potato starch stories support what I’ve said (here and here) about why bedtime honey improves sleep, namely:  You need a certain amount of blood sugar to sleep well. Many people have too little (e.g., due to a low-carb diet). Honey, a banana, or resistant starch near bedtime are three ways to ensure enough. When this becomes well-known, the improvement in well-being will be great.

Bedtime Honey Doubles a Measure of Strength

A reader of this blog named Nile McAdams, who lives in Minnesota, wrote:

When I read your first blog post about honey I was gobsmacked. Not so much by the improved sleep — the idea of a bedtime snack improving sleep has been around a long time — but by the fact that a tablespoon of honey could double the time you were able to stand on one leg. [One bent leg. After being roughly constant for a year, the time doubled in two weeks. — Seth] Impossible!! Not that I thought you were lying — I didn’t — it is just that a lot can go wrong between collecting the data and interpreting the data. So I had to try it for myself. Continue reading “Bedtime Honey Doubles a Measure of Strength”

Why Does Bedtime Honey Improve Sleep? Helpful Data

I speculated that bedtime honey improves sleep because it consists of an equal mix of glucose and fructose. Glucose is used by the brain during the first half of the night. By the second half, the fructose has been converted to glucose. However, honey has other ingredients, so it is not obvious that fructose and glucose are responsible. I focused on them partly because a need for glucose and fructose during sleep would explain (in evolutionary terms) why we eat dessert after meals, a puzzling separation.

Other carbohydrates also increase blood glucose. Do other carbs also improve sleep? Stuart King (who told me how much bedtime honey improved his sleep) pointed me to a 2010 discussion on a body-building forum. One person wrote:

I save a good portion of my carb intake for my last meal as I’ve found I sleep better afterwards. The worst nights of sleep I’d have during my prep were during my low carb days. Brutal.

Which supports the idea that blood glucose is running down, with bad consequences, during sleep. Even more telling was what someone else said:

Why does this happen to me? Before I was eating 2 cups of milk and a banana right before bed and would sleep fine. In the past few days I’ve tried to switch to 1 cup cottage cheese and 2 tbsp natty peanut butter. I’ve figured out this is why these past few nights I’ve had much more trouble sleeping and have had to resort to taking more OTC sleep aids. Then I’ll still wake up in middle of the night and can’t fall back asleep so I end up having a peanut butter and jelly sandwich and a cup of milk and 20 min later fall back asleep and sleep fine through the rest of the night.

Bedtime Snack A (2 cups of milk, banana): Good sleep. Bedtime Snack B (1 cup cottage cheese, 2 T peanut butter): bad sleep. There are hundreds of differences between the two snacks but one is that A, because of the banana, has about 6 g glucose and 6 g fructose (plus 3 g sucrose) and B has neither glucose nor fructose (nor sucrose). Stuart and I and several others have found that one tablespoon of honey (20 g) at bedtime greatly improves sleep. That much honey has about 8 g glucose and 8 g fructose. This is excellent evidence that it is the glucose and fructose in bedtime honey that improve sleep. Further evidence is that a snack with lots of sucrose (jelly) also produces good sleep.

More about bedtime honey and sleep.

 

 

 

Assorted Links

  • No correlation between omega-3 levels and cognitive function. I found strong effects of flaxseed oil (high in omega-3) in experiments, so this finding doesn’t worry me. Maybe the measures of cognitive function in this study depended on too many things they didn’t measure or control.
  • Does methanol cause multiple sclerosis?  Woodrow Monte makes a good case. “In the 1940s, . . . the National Multiple Sclerosis Society found the incidence of the disease to be virtually equally distributed between the sexes. . . . The real sea change in the incidence of MS in women did not come until after the introduction of a brand new methanol source . . . a can of diet soda sweetened with aspartame has up to four times the amount of methanol as a can of green beans. . . . At the 59th annual meeting of the American Academy of Neurology in Boston on April 26, 2007 
  • Honey in human evolution. “Upper Paleolithic (8,000 – 40,000 years ago) rock art from all around the world depicts early humans collecting honey. . . . .The Hadza hunter-gatherers of Tanzania list honey as their number one preferred food item.”
  • What one climate scientist really thinks about Michael Mann. “MBH98 [Mann et al.] was not an example of someone using a technique with flaws and then as he [Mann] learned better techniques he moved on… He fought like a dog to discredit and argue with those on the other side that his method was not flawed. And in the end he never admitted that the entire method was a mistake. Saying “I was wrong but when done right it gives close to the same answer” is no excuse. He never even said that . . . They used a brand new statistical technique that they made up and that there was no rationalization in the literature for using it. They got results which were against the traditional scientific communities view on the matters and instead of re-evaluating and checking whether the traditional statistics were [still] valid [in this unusual case] (which they weren’t), they went on and produced another one a year later. They then let this HS [hockey stick] be used in every way possible . . . despite knowing the stats behind it weren’t rock solid.”  Smart people still fail to grasp the weakness of the evidence. Elon Musk, the engineer, recently blogged, responding to Tesla fires, that Tesla development must happen as fast as possible because if delayed “it will . . . increase the risk of global climate change.”

Thanks to Dave Lull, Stuart King and Joe Nemetz.

Is Diabetes Due to Bad Sleep?

When I started eating honey at bedtime to improve my sleep, my fasting blood sugar values suddenly improved. Alternate-day fasting had pushed them into the mid-80s; now they were often in the high 70s, values I had never seen before. Without long walks and alternate-day fasting, my fasting blood sugar values would have been more than 100, which is pre-diabetic.

This made me wonder: Does bad sleep cause diabetes? Plenty of evidence, I found, supports this idea. Here is one example:

Just three consecutive nights of inadequate sleep can elevate a person’s risk [of diabetes] to a degree roughly equivalent to gaining 20 to 30 pounds, according to a 2007 study at the University of Chicago. . . .This revelation backs up previous research from Yale and the New England Research Institutes, which showed that people who clock six hours or less of sleep a night are twice as likely to develop diabetes in their lifetime as those who snooze seven hours.

Here is another:

In the study, published in the October issue of the Journal SLEEP, short sleepers reported a higher prevalence of coronary heart disease, stroke and diabetes, in addition to obesity and frequent mental distress, compared with optimal sleepers who reported sleeping seven to nine hours on average in a 24-hour period. The same was true for long sleepers, and the associations with coronary heart disease, stroke and diabetes were even more pronounced with more sleep.

Maybe there is something to it.

 

 

 

Bedtime Honey Improves Sleep “1000%. Crazy Good Tip”

On a recent episode of Grumpy Old Geeks, a podcast by Brian Schulmeister and Jason DeFillippo, Jason told what happened when he had honey at bedtime (starts at 1:04:20):

JASON Tim Ferriss posted this . . . I did the experiment. I’ve been doing it for about six days now. Um, yeah, a thousand percent.

BRIAN Really? It’s really helped?

JASON One. Thousand. Percent. I sleep through the night. . . . I can quantifiably tell you that in the morning I am sharper, I get more work done, I am better rested, and I feel a thousand percent better. I’m going with the formula in the article, which is a cup of hot water, mixed with 2 tablespoons of apple cider vinegar and 1 tablespoon of honey. It’s tasty, it’s really tasty, you wouldn’t think vinegar and honey would be great but it almost tastes like an apple cider.

BRIAN That doesn’t sound very appetizing to me, but I’ll trust you that it wasn’t bad.

JASON I found it delicious. And, plus, the hot liquid just before I went to bed, just knocked me out. I fell asleep immediately. . . . I’ve always had problems waking up five or six times in the middle of the night. I have slept through the night ever since I started this. I wake up in the morning ready to go.

BRIAN Excellent.

JASON This is one of the best sleep tips I’ve ever found. . . . The last couple nights I didn’t really have the time, ’cause I was getting kinda tired and I’m just like, you know what, I popped the lid on the honey and poured it down my throat and that feels like 1 tablespoon or 3, whatever. Same effect. . . . I have a tablespoon of honey right before I go to bed. Man, it has really improved how I sleep. Not even that, it’s how I greet the day. I greet the day really just ready to go. I’m a horrible morning person. I hate mornings.

BRIAN [laughs]

JASON If you have problems sleeping, definitely give this a try. Even if you don’t have trouble sleeping. I think it will improve how your body solidifies memory and does muscle rebuilding. They [= Seth and Stuart King] talk about strength improvements and it’s true. It’s ridiculously true. That’s when your muscles heal. . . . . It’s a crazy good tip. So hats off to Tim for passing that one along and I highly recommend it.

BRIAN I don’t have sleep issues . . . but I think I’ll give this a shot anyways and see if I get any of the other benefits.

JASON Yeah, that’s what I’m saying. Even if you don’t have sleep problems, it will still help your brain like, hardcode memories. I’ve found that my memory has really improved. Especially with this project that I’m working on. Before I would wake up and it would take me an hour to get back to where I was  . . . [Now] I come back down in the morning and I come back exactly where I was, ready to rock.

BRIAN Awesome. . . . I will definitely try it out.

Lots of research says better sleep = better memory.

Honey, Sleep and Reddit

Looking at traffic to this blog, I found a discussion on Reddit, in the Paleo subreddit, of my sleep-honey post. “I’m too stupid to know who’s wrong,” said one person. Someone else, not the original poster, said:

I’m not on a paleo diet by any means, but I’ve been taking teaspoons of raw honey before I go to bed this past week strictly because I like the taste. What I have found is a noticeable change in my sleeping. I always wake up with more energy…. regardless if I wake up a couple of times in the night or if I get a full night’s sleep. I’m generally a poor sleeper in that I wake up several times in the night. After taking the honey this past week, I have found out that I wake up less or even get a full night’s sleep. For example, last night I got a teaspoon of honey before bed, and I got an uninterrupted 6 and a half hours of sleep. I woke up so refreshed this morning, I got up and exercised for the first time in so long. I generally exercise in the afternoons because it takes me a bit for me to actually wake up, but I just felt so rested this morning. I noticed these changes lately, but it took this article for me to realize it might be [due to] the honey.

Again, notice that one teaspoon of honey made a noticeable difference. His or her belated realization is like what happened to me. As I said in the original post, now and then I’d sleep really well. It seemed to be correlated with dinner at other people’s houses. I’d sleep better than usual after those dinners. It hadn’t occurred to me until Stuart King told me about his honey experience that those dinners were almost the only times I ate dessert.

Person 2 commented:

I tried it last night and noticed an immediate difference this morning.

Person 3 commented:

Tried the honey thing. While I usually wake up feeling like there is a mammoth sitting on top of me, today I woke up not totally refreshed, but without the mammoth, definitely a good feeling

More About Sleep and Honey: One Teaspoon

One of the comments on my honey-improves-sleep post deserves emphasis:

I tried the honey last night for the first time – just 1 tsp. I’ve been eating very low-carb lately, so no sugar throughout the day at all. . . . When I woke up for the day . . . I felt an incredible sense of well-being. Normally, I wake up with aching hip joints and feeling pretty ugh, but not this morning. My sense is that the sleep was “richer” . . . in the way that heavy cream is different from skim milk.

I asked the commenter for an update. She replied:

I’m still seeing improved sleep. Last night, I think I slept for 8 hours straight, or darn near, which has only been possible with an Advil-PM over the past 6 months or so. One of the notable changes in my sleep is vivid dreams. I recalled them pretty clearly the first night, less so since then; I just know that I’ve been dreaming. I am using approximately 1 teaspoon of honey, taken on the way to bed. Since starting it, I have taken extra care to avoid sugar and starch during the day, as well. I plan to continue it indefinitely.

I too found that one teaspoon of honey made a clear difference, as did Stuart King, who described the effect. I’ve been taking one tablespoon to be sure to get the greatest possible benefit; eventually I will test smaller amounts.

I don’t know of another case where one teaspoon of an ordinary food produces a big improvement. One teaspoon (5 ml) of orange juice has about 2.5 mg of Vitamin C. The daily requirement of Vitamin C is about 80 mg/day. (Whether you should take much more, as some say, is quite unclear.) If you get less than 10 mg/day for a long time, you’ll get scurvy. According to this table, the common foods highest in Vitamin C, such as orange peel, have about 1 mg/g. One teaspoon of honey is 7 g, so from 7 g of a common food high in Vitamin C you’d get 7 mg of Vitamin C. And keep in mind that scurvy is very rare, but bad sleep is common. Which makes the effect of one teaspoon of honey even more striking.

Does Bedtime Honey Improve Sleep? Nine Reasons to Think So

Stuart King, an Australian musician in his thirties, recently commented:

Most days I wake up feeling more tired than when I went to bed the night before, however I find that if I take up to a tablespoon [15 ml] of raw honey immediately before bed I almost always wake up feeling totally refreshed. I’ve suffered from low energy, brain fog, fatigue and sore muscles for years. I tried eliminating food groups (dairy, grains, nightshades, etc) but that didn’t fix the problems (although wheat has been problematic) but taking the honey did. I usually sleep without any problems that I’m aware of — even if I awaken feeling unrefreshed I will still sleep through the night and won’t awaken early or whatever, but the crucial thing is I feel rested when I wake up, if I get that right I can even eat bad food and feel good all day. I tried coconut oil and coconut oil combined with honey but they didn’t work.

I hadn’t heard that before. I searched “health benefits of honey” but didn’t find it.  A Wikipedia entry about the health benefits of honey doesn’t mention it. In China, many people think honey is a health food, yet a Chinese friend of mine, who eats honey daily, hadn’t heard this. The uses of honey in Traditional Chinese Medicine lie elsewhere. Honey as sleep aid is briefly mentioned (with a question mark: “Key to a restful night’s sleep?”) in The Honey Prescription (2010).

Many say or assume something quite different. According to Dr. Mercola, to sleep well “avoid before-bed snacks, particularly grains and sugars”. A Huffington Post writer says, “You already know which edibles to avoid before bedtime — namely, alcohol, coffee and sugary desserts.” Honey is half fructose, which UCSF professor of pediatrics Robert Lustig calls “poison”. Lustig says fructose is “one of the most egregious [= worst] components of the western diet, directly contributing to heart disease and diabetes, and associated with cancer and dementia.”  John Yudkin, a well-known nutrition professor, wrote books about the harm done by sucrose. He considered fructose even worse. Nutrition researchers rarely study time of day effects. For example, nutritional epidemiologists ask what you’ve eaten but don’t ask when.

I found a bit of evidence supporting what Stuart found — namely, two comments here:

Just started honey and vinegar hot drink 2 weeks ago. Am amazed at the increased quality of sleep and relief of night time pain. Thought I was imagining it so did not have my drink one night. Didn’t sleep and was racked with pain again all night. . . [my recipe:]  2 tbsp apple cider vinegar and 1 tbsp honey with 1 cup hot water.

Honey knocks me out and I actually wake up in the morning feeling refreshed and ready for the day–amazing. I’ve been using the honey for a few months now. The difference has been “night and day!”

In addition, a 2007 study found that honey at bedtime was slightly better than no treatment at reducing the symptoms of coughing children. A 2010 study and a 2012 study found the same thing.

I asked Stuart how he discovered that honey improved his sleep. He replied:

I read something that Tim Ferriss said about having a small snack before bed [Ferriss advises protein and fat, not honey — Seth], I think he mentioned that unrefreshed sleep was due to low blood sugar. At the time I was doing carb back loading (I’ve since stopped that as carb restriction gave me problems). I would have a snack before bed but it didn’t always work. I think the small fructose amount in honey was what helped, starches didn’t always help. I did some research and came across your blog and Dave Asprey’s blogs on sleep, Dave mentioned raw honey. He encouraged people to take MCT oil with the honey to stay ketogenic, I tried coconut oil with the honey instead but it didn’t work. If anything it made my sleep worse with stomach cramps. I think there is an amount where benefits end, I think anywhere between a teaspoon or a tablespoon is about right. . . . The first time I did it I couldn’t believe it, I felt so good the next day.

He added later:

I have noticed that if I eat a lot of sugar during the day (soft drinks, desserts and so forth) then I don’t feel refreshed [when I wake up] regardless of the honey. Perhaps there’s something about honey that helps regulate blood sugar. I think it works better on an empty stomach/lightly fasted. So if you had dinner at 7 pm you might not eat anything after and take the honey at 9 or 10. In the past I’ve had a late dinner then maybe some dessert or fruit in the following hours, then added the honey just after and I don’t think it worked as well. When I first tried it I used commercially available heated honey and it worked great. I’ve tried 2 tablespoons, but I don’t think that worked any better than one and sometimes as little as 1 teaspoon is enough.

In summary, three people reported great improvement in sleep from honey at bedtime. Stuart found several other things: 1. If he ate a lot of sugar during the day, the effect went away. 2. Other carbs didn’t work. 3. An empty stomach was important. 4. Effective doses ranged from 1 teaspoon to 1 tablespoon.

I believe Stuart has discovered something very important. My belief rests on several things:

1. Repetition. I started eating honey (1 tablespoon) at bedtime. My sleep (much better than Stuart’s to begin with) clearly improved, even with 1 teaspoon. I felt more rested when I awoke and more rested throughout the day. The improvement happened night after night. One evening I didn’t eat the honey on an empty stomach. The improvement didn’t happen, just as Stuart would have predicted. I told a friend about it. He took 1 tablespoon at bedtime. His sleep immediately improved by a large amount. He stopped waking up in the middle of the night and stopped needing a nap in the afternoon. Another friend has tried it once (so far). “When I woke up the next morning,” she wrote, “I’d realised I’d slept all the way through the night without waking up in the early morning (a nice change) but had a terrible case of the jitters (a not-so-nice change).” A third friend tried it twice. She slept better the first night but not the second. Maybe she failed to eat it on an empty stomach or had too many sweets during the day.

2. Strength increase. As soon as I started the honey, I got stronger — a complete surprise. For years I have done one-legged standing to exhaustion several times per day because it improves my sleep. To reach exhaustion sooner, I stand on one bent leg. Recently I’ve been doing it four times per day (right leg twice, left leg twice). For a year, I’ve averaged about 3 minutes to exhaustion. After I started the honey, the length of time until exhaustion quickly increased. Here are the measurements:

 photo 2013-11-02effectofhoneyatbedtimeonone-legstanding_zps41d50272.jpeg

Each point is a different day; each is the average of the two durations for the first right and first left leg standing of the day. The 2013 tick marks the start of 2013. Nothing changed except the honey. The strength increase was also clear in other ways. In Beijing, I live on the sixth floor of a walk up. It became noticeably easier to climb the six flights of stairs.

The strength increase astonished me. The dietary change was tiny, did not happen before exercise, and involved a safe widely-available food (in contrast to the drugs athletes use, such as steroids). I believe better sleep increased muscle growth. I predict that taking the honey at other times, such as in the morning, would not have the same effect. My earlier observations that lots of standing  and one-legged standing improve sleep make more plausible causality in the opposite direction: something that improves sleep will increase muscle growth.

When I described my strength increase to Stuart, he replied:

I have noticed that when I do the honey, my weight goes up over the next week or two, perhaps by 400-500 grams [yet] my waist doesn’t increase (I measure it with a tape measure) even after a few weeks. I also have been sure that I noticed rapid muscular growth around my chest, shoulders and arms, similar to what I have noticed when going hard at the gym after a few months off. I kind of assumed that maybe I had more stored muscle glycogen from the honey, but had also considered that improved sleep as you said was the reason.

3. Evolutionary explanation. It has been a mystery why evolution shaped us to like sweetness so much. Israel Ramirez (whose research led to the Shangri-La Diet) pointed out that the usual explanation (sugar is a  source of energy) makes no sense.  If it’s because sugars provide energy, why don’t potatoes and rice taste just as good? They don’t. Nutritionists lump sugars with other carbohydrates, thereby ignoring the puzzle. No anti-sugar advocate — not Yudkin, Lustig or anyone else — has provided a good explanation of why evolution shaped us to like the taste of a “poison”.

There are several related puzzles. Why are meals divided into main course and dessert? In other words, why do we eat the sweet part separate and later? If we like sugars because they provide energy, this makes no sense. If sugars are simply carbs, this makes no sense — we eat plenty of carbs during the main course. The separation of dessert and main course, if it reflects brain mechanisms, must mean that sugars are quite different than other carbs. Somehow we benefit from this division. A few people, in particular Elizabeth Capaldi, an experimental psychologist, have figured out that sweet food tastes worse if we are hungry (enough). This is why dessert comes after the rest of the meal. Yet other carbohydrates do not taste worse. Stuart pointed out something else along these lines, which I had not heard before but which is clearly true: We eat dessert much more after dinner than after lunch.

Stuart’s observations explain these mysteries. All four observations (liking for sweetness, separation of main course and dessert, sweet things taste bad when hungry, dessert after dinner but not lunch) make sense if we have evolved mechanisms to push us to eat sweet foods near bedtime. Long ago, these foods would have mainly been fruit. Because sleep is so important for health, there would be powerful selection for anything that improved sleep.

4. Basic physiology. The brain runs on glucose. In my brain tests, sugar drinks, cupcakes, and other sugar-rich foods make an obvious difference 30 minutes to 2 hours later. (I get faster.) And the brain controls sleep, an enormously complicated and time-sensitive process. Too little blood sugar during sleep could easily disrupt sleep.

5. Basic nutrition. Honey is half glucose, half fructose. When you eat it, the glucose enters the blood quickly and would supply glucose to the brain in the first half of the night. In contrast, the fructose turns into glucose and enters the blood slowly (fructose has a low glycemic index). This would supply glucose to the brain in the second half of the night. Many fruits, such as bananas, figs, and grapes, have a similar composition (similar amounts of fructose and glucose). Most fruits have plenty of fructose and glucose.  A 50/50 glucose/fructose mixture makes honey near the start of sleep a good source of blood glucose over an extended period without food. Notice that you need both — glucose and fructose — in roughly equal amounts to get a roughly steady supply over six or seven hours.

6. Basic engineering. When you are asleep, there can be no “course correction”. You must subsist for the next six or so hours without any behavioral help, such as drinking water when thirsty. So it makes design sense to do something shortly before sleep that will provide a relatively steady supply of glucose throughout the night (“time-release”). That won’t be a lot of glucose at once. You need a food that is a mix of sugars.

7. Support for general idea. A few weeks ago a woman told me that when she ate very low-carb her sleep suffered, so she ate more carbs and her sleep got better. This supports the general idea behind what Stuart found — that the brain needs a certain amount of glucose to work well during sleep and it is best if it gets at least some of it from carbohydrate.

8. Explanation of correlation of sugar and bad health. Why is sugar consumption often correlated with poor health? This is easy to explain: sugar at the wrong time is the problem. Too much sugar during the day interferes with the bedtime benefit (and may also interfere with sleep in general). Stuart found exactly this: Eating lots of sugary foods during the day disturbed his sleep and eliminated the honey effect (“if I eat a lot of sugar during the day . . . then I don’t feel refreshed [when I wake up] regardless of the honey”). Too much sugar during the day could make it harder to get optimal glucose levels during the night. For example, too much sugar during the day might raise insulin levels, causing too-low blood sugar at night and/or causing a fructose/glucose mixture eaten at bedtime to be digested too quickly. Anything that harms sleep will increase disease. Good health, good sleep and good immune function are closely connected. An example of the evidence is that shift workers get more cancer than non-shift workers.

9. Reichenbach’s Common Cause Principle, in my paraphrase, is lightning doesn’t strike twice in one place for different reasons. If two rare events might have the same cause, they probably do. In this case, lightning has struck three times in one place. 1. Huge sleep improvement from tiny dietary change. 2. Huge strength improvement from tiny dietary change far from time of exercise. 3. Evolutionary explanation of why sugars taste good, why dessert exists and follows the main course, and so on. Before this, no one has come close to a plausible evolutionary explanation. The absence of an explanation is remarkable because two of the phenomena — sweetness tastes good, sweets are eaten separately after the rest of the meal — are so obvious.

I believe Stuart’s discovery is important for two other reasons that might not impress anyone else. One is similarities with my earlier work. First, I’ve found  other “cross-over” interactions with time of day, where something helpful at one time is harmful at another time. Vitamin D in the morning improves sleep, Vitamin D at night harms sleep. Morning faces improve mood, evening faces harm mood. Second, wondering why we like sour, umami and complex flavors was the first thing to suggest to me that we need to eat plenty of fermented food to be healthy. Many facts later, I’m sure this is true. Finally, evolutionary reasoning has helped me find several new experimental effects (morning faces, Shangri-La Diet, flaxseed oil, standing and sleep).

Finally, Stuart’s discovery explains something puzzling I’d noticed repeatedly for years. Now and then I slept unusually well. I’d wonder why — how was yesterday different from usual? — and see that the only unusual thing was that I’d had dinner at a friend’s house. At the times, I guessed that seeing faces in the evening was somehow improving my sleep. This did not make sense in terms of my morning faces work, but a connection between social contact and sleep was well-established. Now I realize that dinner at a friend’s house is one of the few times I eat dessert. A friend told me that when his partner has dinner parties, she serves dessert long after the main course.

This report suggests that different honeys may differ in important ways.

I told a Dutch friend about this. She said it was common in Holland to have milk and honey at bedtime, although she herself didn’t do this. I asked why. No clear reason, she said. An excuse to have something sweet? Could this be why the Dutch are so tall? Children grow when asleep. Better sleep, more growth. My strength increase suggests what a big effect this could be.

More posts about honey and sleep.