Just a week of inadequate sleep can alter the activity of hundreds of genes, which may help scientists explain how wakeful nights can lead to ailments such as diabetes, obesity and heart disease.
Blood samples taken from patients revealed genetic changes that, with further research, may help answer why sleepless nights are so harmful to health, according to the study published today in the Proceedings of the National Academy of Sciences. While not all of the altered genes have known functions, some are involved in metabolism and stress response.
More than one-third of Americans sleep fewer than seven hours a night, affecting their ability to concentrate, according to the U.S. Centers for Disease Control and Prevention. When people don't get enough sleep, have poor-quality rest, or sleep at the wrong times of day, they are at a higher risk of heart disease, kidney disease, high blood pressure, obesity, diabetes and depression, according to the National Institutes of Health.
"These pathways are ones investigators can pursue," said Louis Ptacek, a neurologist at the University of California, San Francisco, who wasn't affiliated with the research. "These genes are interesting, why is the rhythm dampened?"
Most adults need seven hours to nine hours of rest each night.
In the study, 26 participants spent a week sleeping fewer than 6 hours each night and had their blood drawn for samples. They then were kept busy for 40 hours and allowed to recover. The next week, they were allowed to sleep as many as 10 hours a night, and their blood was drawn again. The scientists used RNA extracted from patients' blood to measure the effect on genes.
Changes were seen in more than 700 genes. In addition, about 374 of the 1,855 genes that ordinarily peaked and waned during the day also had their functions altered. Among the genes affected were those known to be involved with circadian rhythms, stress, how the body regulates itself while it sleeps, and metabolism.
It's not clear how many of those changes were due specifically to lack of sleep, or to the stress caused by a lack of sleep, Ptacek said. A next step might be to compare the responses of people with chronic stress with those who are sleep deprived, he said.
While the participants were awake, their performance was assessed. When people in the group didn't get enough sleep, they suffered more lapses in attention than when they had an adequate amount of rest, the study found.
The research was led by scientists at the University of Surrey in Britain. It was funded by the U.S. Air Force Office of Scientific Research.
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