LOS ANGELES — Doctors know that being chronically sleep-deprived can be hazardous to your health. Night-shift workers, college crammers and all the rest of us who get less than our fair share of zzz’s are more likely to be obese and to suffer cardiovascular woes than people who get a consistent, healthful eight hours.
Now scientists have some new clues about how lack of sleep translates into disease.
After subjecting 26 volunteers to seven nights of insufficient shut-eye followed by a marathon all-nighter, researchers detected changes in the way hundreds of genes were expressed in their bodies. Some genes, including damage-inducing ones involved in stress reactions, were amplified. Others, including many that nurture and renew cells and tissues, were turned down.
“It’s possible to see how that contributes to poor health,” said Colin Smith, a genomics researcher at the University of Surrey in England and one of the senior authors of a report detailing the findings this week in the journal Proceedings of the National Academy of Sciences.
Scientists have long puzzled over the purpose of sleep. For years they focused on how it influenced the brain, said Derk-Jan Dijk, a sleep and circadian rhythm researcher at the same institution and the study’s other senior author.
But epidemiologists noticed that people who work early in the morning or late at night — or who lack sleep in general — have higher rates of diabetes, stroke and high blood pressure, among other ailments. And biologists have discovered that people who get poor sleep produce more of the stress hormone cortisol and the appetite stimulating hormone ghrelin, among other biochemical changes.
“It used to be thought that sleep was by the brain, of the brain, for the brain,” said Dr. Charles Czeisler, a Harvard Medical School researcher who is known for his examinations of how poor sleep affects people in a variety of everyday settings. “Now it’s recognized that it plays an important role in bodily functions.”