Category Archives: Medicine

So Much for the Germ Theory: Scientists Demonstrate That Sleep Matters More Than Germs

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More in a continuing series about one of my favorite topics, something we all do every day, and spend roughly a third of our lives doing…sleep!

Since we are in the middle of the common cold season, this post will be particularly relevant.

It turns out, grandma was right. Getting good sleep really does prevent colds. This supports a favorite belief of mine—that I don’t believe in the germ theory of illness.  Read on and you will see why I liked the referenced article.

Researchers at a variety of universities collaborated and did a clever study looking at sleep and its effects on susceptibility to the common cold. First they had their 153 subjects, healthy men and women between 21 and 55, report their sleep duration and efficiency for 2 weeks. (Efficiency is what percent of the time you are actually sleeping while in bed.) Next, these diabolical researchers sprayed cold virus up the noses of all the subjects (in quarantine), and watched what happened over the next 5 days.

The results were very interesting. Those subjects who slept less than 7 hours were almost 3 times more likely to develop a cold than those who slept 8 hours or more. In addition, those whose sleep was less than 92% efficient were 5.5 times more likely to develop a cold than those with 98% or more sleep efficiency. Interestingly, how rested subjects reported feeling after sleep was not associated with colds.  The lead author of the study concluded, “The longer you sleep, the better off you are, the less susceptible you are to colds.”

Now I promised that I would report evidence that this study bolsters my theory that germs don’t really matter that much. Remember the researchers sprayed virus up everyone’s noses. After five days, the virus had infected 135 of 153 people, or 88% of the people, but only 54 people (35%) got sick. What this suggests is that even among the people who were infected with cold virus, 60% stayed healthy, while 40% got sick. And the ones who got sick were much more likely to have reported less and lower quality sleep in the two weeks before infection. 

This is very relevant for everyday life, since much of the time we can’t really avoid exposure to common germs like colds and flu. If good sleep protects us even when infected with such germs, then it may be the key to staying healthy.

What is truly fascinating about this study is the precise immune regulation showed by those who got infected, but stayed healthy. To understand this let me digress for a moment with a short primer on the common cold. Most people think cold symptoms are caused by cold virus. This is wrong. Actually, cold symptoms are caused by our bodies’ immune reaction to the cold virus. Our bodies produce germ fighting proteins called cytokines, and when our bodies make too much, we get the congestion and runny nose symptoms. If our bodies make just the right amounts of cytokines, we fight the virus without feeling sick.

So getting 8 or more hours of sleep a night may allow your body to fine tune an immune response, and make just the perfect amount of germ fighting proteins.

Another interesting finding is the relationship of sleep efficiency and illness. Sleep efficiency was an even more powerful predictor of getting sick than total sleep. (Of course, this might reflect an overall difference in sleep quality. Those who sleep deeply may tune up their immune systems better, and they are likely to spend most of their time in bed asleep.)

But assuming that increasing sleep efficiency is useful, then those people who take a long time to fall asleep, and who sleep fitfully may benefit from spending less time in bed, and working on sleeping more of the time they are in bed. On the other hand, those who fall asleep as soon as their head hits the pillow, and who are sleep like logs, would probably benefit from spending a little more time in bed, since they are not getting enough sleep.

So there you have it. Sleep 8 hours or more, try to sleep well, and you can lower your odds of getting a cold greatly. Even if you are exposed to the virus, if you have good sleep quality, you probably won’t get sick. So much for the simple germ theory! I suspect that this applies to all infectious diseases. So getting good quality and quantity in sleep may be one of the most important health behaviors for staying well.

It’s late, and I’m off to bed now…..zzzzzzzzzzzzzzz.

Copyright © 2009 The Psychology Lounge/TPL Productions/Andrew Gottlieb

Followup on the Science of Sleep

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It’s been a while since I wrote, and some of that is that I’ve been trying to get to bed earlier, and get a more consistent 8 hours of sleep. Since I last wrote, I saw an interesting factoid from an interview with Daniel Kripke, who is the co-director of the Scripps Clinic Sleep Center in La Jolla, California. In this interview, he talked about research he did on more than 1 million Americans that correlated sleep and mortality. There were some surprising findings, which have been corroborated by similar studies in other countries.

The results showed that those who slept between 6.5 and 7.5 hours a night lived the longest. And that those who slept more than 8 hours a night or less than 6.5 hours a night don’t live as long. This is interesting in that most previous writing I have seen suggests that sleeping more is good for you, but these data don’t support that.

Another good point he made was that when people try to get too much sleep, because they think the normal amount is 8 or 9 hours, they may unintentionally develop insomnia. Staying in bed longer than you can sleep will result in wakefulness, and anxiety about not being able to sleep. So for those of you who only can sleep 6.5 or 7 hours, just get up, it won’t hurt your health. In fact, restricting the time in bed is a more effective treatment for insomnia than sleeping pills, according to Kripke.

What we don’t know is which direction the causality runs in this association. Does the amount of sleep you get create your health status, or is it a reflection of underlying health? Do sicker people sleep too little or too much? Or does sleeping too little or too much make you sicker? No one knows for now, so I wouldn’t necessarily rush to change your sleep habits based on this study. But if you are sleeping in the 6.5 to 7.5 hour range, you can relax and not worry about it (especially late at night!)

Now I’ve got to stay up a little longer, so I don’t get too much sleep tonight…

Copyright © 2008 The Psychology Lounge/TPL Productions

The Mystery of the Obesity Epidemic: Solved? (Hint: It’s simpler than you think)

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Was Grandma Right?

It’s been too long since I last wrote, but I’ve been catching up on my sleep. Why will become relevant after you read this article.

Sleep is something we mostly take for granted as part of our daily lives, much like eating and showering. But why do we sleep? What does sleep do for our minds and our bodies? What happens if we don’t sleep, or if we don’t sleep enough?

For those of you who are interested in these questions, I’d highly recommend that you read the transcript of The Science of Sleep, an excellent piece by 60 Minutes that aired on March 16, 2008. Not only did I learn many interesting facts about sleep, I learned about my own health and how sleep affects it. More on that later.

Why do we sleep? After all, from a survival point of view, sleep is not really a good thing, in the sense that we are unconscious and helpless during sleep. So for sleep to have evolved, then it must serve some vital functions. (I should point out though, that sleep might have survival advantages, since if early humans slept in caves and other sheltered places, sleep would have kept them out of the reaches of nocturnal predators. The folks who didn’t sleep much, and who wandered around all night, probably got eaten!)

One clue of how important sleep is in studies done in the 1980’s with rats. When rats were prevented from sleeping (did they use disco music to keep them awake?) they died after 5 days! Sleep seems to be as important to rats as food.

Let me present a quick primer on sleep. When we sleep, we actually go through multiple cycles of different stages of sleep. These stages are stages 1-4 of non REM (NREM) sleep, and stage 5 which is REM (rapid eye movement) sleep. The key stages are Stage 4, or Delta Sleep, and Stage 5, REM sleep. Stage 4 Delta sleep is the deep restorative sleep where our bodies get rebuilt and restored. Stage 5 REM sleep is when we dream, and it appears that our minds get restored during REM sleep. Typically the whole cycle takes about 100 minutes, and we have 3 or 4 of them each night.

Sleep may play an important role in enhancing memory. One study found that when people learned a new skill in the afternoon, and then were tested after a night of sleep, they did 20-30 percent better than those who were tested after twelve hours, but with no sleep in between the learning and testing. This is fascinating, and jibes with a trick I learned in graduate school. When I would study statistics, I’d always review my notes right before going to sleep. The next morning, the memories of those notes were imprinted magically in my mind.

Sleep also plays a critical role in stabilizing mood. One experiment tested people who were sleep deprived by showing them disturbing images within an fMRI scanner, to look at their brain activation. They found the sleep deprived subjects had a disconnect between the brain’s emotional center (the amygdala) and the part of the brain that controls rational thought (the frontal lobe). So they couldn’t control their emotional reactions. They looked more like psychiatric patients. Of course we all know that sleep deprivation makes us cranky and short-tempered, this explains why.

Another important function of sleep is physical rejuvenation. It appears that Stage 4 sleep is essential here. In the 60 Minutes piece they show an experiment where a young man named Jonathan is deprived of only Stage 4 sleep. Each time his brain waves show Stage 4 sleep, loud sounds are played to bring him out of deep sleep. He gets a normal amount of sleep, but a reduced amount of Stage 4 sleep. After 4 nights of this regimen, this 19 year old is starting to look physically like a 70 year old. His body becomes no longer able to metabolize sugar effectively, putting him temporarily at increased risk for Type 2 diabetes.

Other studies confirm this. After just a few nights of partial sleep deprivation, young healthy people show a metabolic change that is similar to what happens as people develop Type 2 diabetes. They no longer metabolize sugar effectively. They deposit more fat. The hormone leptin, which controls appetite, seems to drop, and they want to eat more.

This is truly astonishing. If relatively short term sleep deprivation can cause such a profound shift in the body’s sugar metabolism, then this may be the key to unlock one of the great medical mysteries of the 20th century: Why obesity has increased so rapidly since 1980? Could it be that the obesity epidemic is really a sleep deprivation epidemic? Could it be so simple? Not junk food, television, lack of exercise, and all of those things that people talk about? Could grandma have been right?

Here’s the clue.

In 1960 a survey of a million Americans showed an average of 8.0 hours of sleep per night. Today similar studies show we are only getting 6.7 hours a night. That’s a drop of 16.25% in less than a generation. And teenagers are the most sleep deprived of all, since they require 9-10 hours of sleep, and most get less than 7 hours of sleep, thanks to ridiculously early school start times. Teenagers may be lacking between 22 percent and 30 percent of their needed sleep.

So we have a plausible explanation for why everyone, even children and teenagers, is getting fatter. Sleep deprivation causes shifts in metabolism, creating a pre-diabetic state, and lowering level of the satiety hormone leptin, which causes us to eat more, and store more fat. Add sugary or high carbohydrate foods, and we get even fatter. Add inactivity, and we get even fatter. The damage begins early, perhaps in early teenage years.

So if we want to lose weight, then the old saw of a healthy diet and plenty of exercise may be wrong. The proper advice is probably lots of sleep, a reasonably healthy diet, and a little exercise. Or since exercise improves sleep quality, sleep, exercise, and diet. Without adequate sleep, diet and exercise are doomed to failure, since even young people may unintentionally be turning their bodies pre-diabetic, which makes it very hard not to gain fat.

So that’s why I haven’t written. After a lifetime of staying up late, and cheating sleep, I’m starting to try to get a solid 8 hours of sleep a night. Already I’ve lost a few pounds, even though I haven’t been exercising much. The other advantage of going to bed earlier is that when you are sleeping you are not eating.

So try it. Get 8 or 8 1/2 hours of sleep a night. And make sure your teenagers get 9 or 10 hours a night. No more websurfing or TV late at night. And write me and let me know if your weight drops as a result.

Now I’ve got to stop writing and go to sleep…

Copyright © 2008 The Psychology Lounge/TPL Productions

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