![]() In the most famous attempt to figure out why we sleep, in the 1980s, Rechtschaffen forced rats to stay awake in his University of Chicago lab by placing them on a disk suspended on a spindle over a tank of water. Do they literally die from lack of sleep? And if not, to what extent does sleeplessness contribute to the conditions that kill them? Some researchers have found that sleep deprivation impedes wound healing in rats, and others have suggested that sleep helps boost the immune system and control infection. A lot of interest has focused on what exactly kills them, but we still don’t know. Sleep is likely to have physiological purposes too: That patients with FFI never live long is likely significant. So the purpose of sleep may be to help us remember what’s important, by letting us forget what’s not. Giulio Tononi, a noted sleep researcher at the University of Wisconsin, Madison, published an interesting twist on this theory a few years ago: His study showed that the sleeping brain seems to weed out redundant or unnecessary synapses or connections. Such studies suggest that memory consolidation may be one function of sleep. Other researchers have found that the sleeping brain appears to repeat a pattern of neuron firing that occurred while the subject was recently awake, as if in sleep the brain were trying to commit to long-term memory what it had learned that day. They found that those who had engaged in REM sleep subsequently performed better in pattern recognition tasks, such as grammar, while those who slept deeply were better at memorization. Recently, researchers at Harvard led by Robert Stickgold tested undergraduates on various aptitude tests, allowed them to nap, then tested them again. How does sleeping help the brain? The answer may depend on what kind of sleep you are talking about. This idea derives in part from common sense-whose head doesn’t feel clearer after a good night’s sleep? But the trick is to confirm this assumption with real data. The predominant theory of sleep is that the brain demands it. What can possibly be the payback for such risk? “If sleep doesn’t serve an absolutely vital function,” the renowned sleep researcher Allan Rechtschaffen once said, “it is the greatest mistake evolution ever made.” An animal must lie still for a great stretch of time, during which it is easy prey for predators. Fish, reptiles, and insects all experience some kind of repose too.Īll this downtime comes at a price. When mallard ducks sleep in a line, the two outermost birds are able to keep half of their brains alert and one eye open to guard against predators. A dolphin sleeps with half its brain awake so it can remain aware of its underwater environment. We know that all mammals and birds sleep. We have known for 50 years that we divide our slumber between periods of deep-wave sleep and what is called rapid eye movement (REM) sleep, when the brain is as active as when we’re awake, but our voluntary muscles are paralyzed. We know that seven to nine hours after giving in to sleep, most of us are ready to get up again, and 15 to 17 hours after that we are tired once more. And we know that no matter how much we try to resist it, sleep conquers us in the end. If we don’t know why we can’t sleep, it’s in part because we don’t really know why we need to sleep in the first place. But in one respect, it’s a lot like the less serious kinds of insomnia plaguing millions of people today: It’s pretty much a mystery. FFI is exceedingly rare, known in only 40 families worldwide. Before FFI was investigated, most researchers didn’t even know the thalamus had anything to do with sleep. But they don’t know why this happens, or how to stop it, or ease its brutal symptoms. After years of study, researchers have figured out that in a patient with FFI, malformed proteins called prions attack the sufferer’s thalamus, a structure deep in the brain, and that a damaged thalamus interferes with sleep. ![]() I would allow myself to give up.”įFI is an awful disease, made even worse by the fact that we know so little about how it works. “I was afraid that if I knew that this was something I had, I would not try as hard in life. Dinges has declined to be tested for the gene. The syndrome usually strikes when the sufferer is in his or her 50s, ordinarily lasts about a year, and, as the name indicates, always ends in death. First the ability to nap disappears, then the ability to get a full night’s sleep, until the patient cannot sleep at all. ![]() The main symptom of FFI, as the disease is often called, is the inability to sleep. She belongs to a family carrying the gene for fatal familial insomnia. ![]() Unauthorized use is prohibited.ĭinges may face an even harder fight in the years ahead.
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