The secrets of sleep
It's a mystery, but it clearly makes us smarter and healthier
Even as debate continues on sleep and learning, new research is showing that sleep is essential not only to brain function but to the proper function of every bodily organ. From a central command post in the hypothalamus, the brain tells us when to go to bed and when to wake up, all the while regulating body temperature, blood pressure, hormone production, digestive secretion, and immune activity. But in addition to the brain's central circadian rhythm control, researchers now know there are at least eight other clock genes in the body's cells that occasionally go off on riffs of their own.
Out of sync. Consider the gut. "When I go to Europe or Japan, my sleep-wake cycle gets back in sync before my digestive system," says Richard Stevens, cancer epidemiologist at the University of Connecticut Health Center. Without getting too graphic about regular morning digestive tract functions, every time-zone crosser can relate to a gut that seems to have its own strong circadian rhythm. In addition to explaining why the first cup of coffee doesn't have the same effect upon landing in Paris that it did the morning before at home, these other clock genes might explain why heart attacks peak in the morning or why the timing of cancer chemotherapy may improve the odds of survival.
Researchers can point to a whole list of diseases connected to sleep deprivation. A 67-year-old man with prostate problems wakes up to go to the bathroom half a dozen times a night, and one morning he has a heart attack. A 19-year-old college student with a diagnosis of bipolar disorder has too much energy to sleep for five nights running and spins into an episode of uncontrolled mania. A healthy man of 30 gets half his required sleep--four hours a night--for a week and ends up in a prediabetic state with the metabolism of his grandfather. An 82-year-old woman falls and breaks her hip, possibly for the same reason that a 42-year-old truck driver slams into a barrier at 3 a.m.--inattention and slowed response because of chronic partial sleep deprivation.
The need for sleep is so strong that without enough of it "people can't even muster enough willpower to stay awake to save their lives," says Carol Everson, who studies sleep in laboratory rodents at the Medical College of Wisconsin in Milwaukee. Inadequate sleep comes with a high cost.
Perhaps the most graphic example of the link between sleep and illness is bipolar disorder, or manic-depression. "I've always believed the mania caused the lack of sleep, and the lack of sleep worsened the mania," says Alexis Maislen, 27, who was diagnosed with the disorder at the age of 19. It is a disease that cycles moods between boundless highs and incapacitating lows. During the highs, she had so much energy that she'd put on her in-line skates and zip around Boston during the wee hours of the morning. She slept maybe a half an hour a night and couldn't talk fast enough to keep up with her crackling ideas. Finally the words came faster than the thoughts behind them. Friends told her she didn't make sense.
advertisement
