Harvard study on the importance of sleep:
Van Cauter also showed that sleep-deprived subjects had reduced levels of leptin, a molecule secreted by fat cells that acts in the brain to inhibit appetite. “During nights of sleep deprivation, you feel that your eating goes wacky,” says Stickgold. “Up at 2 a.m., working on a paper, a steak or pasta is not very attractive. You’ll grab the candy bar instead. It probably has to do with the glucose regulation going off. It could be that a good chunk of our epidemic of obesity is actually an epidemic of sleep deprivation.”
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Your mother was right: You’ll get sick, become fat, and won’t work as well if you don’t get a good night’s sleep. So make time for rest and recovery. Stickgold likes to compare two hypothetical people, one sleeping eight hours, the other four. The latter person is awake 20 hours a day, compared to 16 hours for the first. “But if the person on four hours is just 20 percent less efficient while awake, then in 20 hours of waking he or she will get only 16 hours of work done, so it’s a wash,” he says. “Except that they are living on four hours of sleep a night. They’re not gaining anything, but are losing a huge amount: you’ll see it in their health, their social interactions, their ability to learn and think clearly. And I cannot believe they are not losing at least 20 percent in their efficiency.”