The neurological consequences of major sleep deprivation are pretty well-known — so much so that we can actually track the order in which you lose various faculties as you stay awake for extremely long periods of time (after 24 hours, your focus goes haywire; after 36, your memory fails; and going without sleep for 72 hours creates a risk of hallucinations). But we're increasingly discovering that there are other ways in which getting insufficient shut-eye can hurt your health, whether you're an adult or a nap-deprived kid. (No, really.) It's far more than just a bit of lost sleeping time; spending fewer hours in bed than you should can damage your brain development, your eating habits and your gut, if new studies are to be believed.
What actually qualifies as "sleep deprivation" can vary from study to study, though between three and five hours of sleep generally counts. And we're still not sure regarding a number of details, like whether deprivation and its effects alter from person to person (the studies I talk about in this article are mostly very small in their focus). But in general, it seems that when we don't get enough sleep, we're risking more than just a cranky morning.
Sleep Deprivation Causes More Calorie Intake — In Both Adults And Kids
A variety of studies released in the past few months have documented something that many of us probably know instinctively: the more sleep-deprived you are, the more calories you consume the day afterwards. And it turns out this phenomenon doesn't just occur among sleepy adults; it also shows up among young children who are sleep-deprived, indicating that it's actually something innate in humans, rather than a coping mechanism that we might learn as we grow.
One of the studies was actually a meta-analysis: it looked at 11 different studies done in a variety of places to see what happened to peoples' dietary intake the day after some really poor sleep. In adults, the results are pretty startling: people who were intentionally sleep-deprived and given only three to five hours of slumber consumed, on average, 385 extra kcal the next day (the equivalent of a bowl of whole-grain pasta), without an increase in physical activity. The other study was conducted exclusively on 10 preschool children, all of whom were 3 or 4 years old and were used to the regular ritual of nap time at their daycare. They were deprived of three hours of their normal sleep (no nap at all, and a later bedtime), and watched to see how their consumption changed. While they were being deprived of sleep, the scientists found, the kids consumed about a quarter more carbohydrates, sugar and calories in total than they would have done on a normal day.
We're not entirely sure why exhaustred people crave more food; people without sleep might be grumpier and more in need of the mood-lift of a snack, their hunger pangs might be out of whack with the natural flow of the day, or it might be caused by some other factor we don't understand yet. But at the moment, it looks like not getting enough sleep is encouraging extra nibbling that isn't necessarily in line with our actual nutritional needs.
It's Bad For Child Brain Development
Yes, your parents were right, go apologize to them right now. It turns out that, according to a small study of 13 different five to 12-year old children, conducted by the University of Zurich, sleep is particularly important for the developing brain. The study's researchers fastened electrodes to the skulls of the participating children as they slept at home, and discovered that, in kids, the brain regions that are still developing are most affected by sleep deprivation.
The need for sleep in exhausted adults tends to show up in the actions of the prefrontal cortex, but in the children of the study, it didn't turn up there at all. It was more pronounced in the developing parts at the back of the brain, and was also associated with the levels of a material called myelin, which develops in our brains as we age and increases the speed of our neural connections. The fact that sleep deprivation hit the most vulnerable bits of the young brains hardest indicated that good sleep is pretty necessary for brains to grow properly; keeping kids up all night might harm their neural development.
It Changes Our Gut Microbes, Which Affects Our Health
There's been a bunch of new science illuminating how the microbes lying around in our gut are important for our general health; microbes have been linked to everything from brain functionality to how much we weigh, and some think that routine analyses of gut bacteria will be "the future of medicine." And in another point for the gut-busters (sorry), a new study has revealed there's a link between sleep deprivation and your gut flora.
The study, mounted by Uppsala University, found that sleep deprivation in adults created physical changes in the composition of bacteria in the gut. So far, so disgusting, but it's not the end of the story. The scientists looked at nine different participants and tested how their gut flora seemed to change as they were forced to sleep for only four hours per night for two nights in a row. The result? The diversity of bacteria didn't change, but it seemed that certain bacteria reacted poorly to the lack of rest; the scientists aren't entirely sure what the reactions might mean for longer-term health consequences. Interestingly, they also found that after the two-day experiment, the subjects had a 20 percent drop in sensitivity to insulin, but they don't think that's related to gut reactions.
The reality is that these studies are all pretty small; only testing a handful of people doesn't prove conclusively that these things are absolutely true for everybody. But they provide small pieces of a bigger puzzle we're beginning to understand: that sleep deprivation has effects much wider than our inability to focus on our breakfast the next morning.
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