Researchers says that, the function of sleep is not just to give rest to the brain even our fat cells need sleep to function properly.
They have found that not getting enough shut-eye has a harmful impact on fat cells, reducing by 30 percent their ability to respond to insulin, a hormone that regulates energy.
Sleep deprivation has long been associated with impaired brain function, causing decreased alertness and reduced cognitive ability.
The study suggests that sleep's role in energy metabolism is at least as important as it is in brain function.
"We found that fat cells need sleep to function properly," said study author Matthew Brady, PhD, associate professor of medicine and vice-chair of the Committee on Molecular Metabolism and Nutrition at the University of Chicago.
Brady said body fat plays an important role in humans.
"Many people think of fat as a problem, but it serves a vital function. Body fat, also known as adipose tissue, stores and releases energy. In storage mode, fat cells remove fatty acids and lipids from the circulation where they can damage other tissues. When fat cells cannot respond effectively to insulin, these lipids leach out into the circulation, leading to serious complications," he explained.
"Sleeping four to five hours a night, at least on work days, is now a common behavior" said study author and sleep specialist Esra Tasali.
"Some people claim they can tolerate the cognitive effects of routine sleep deprivation," said co-author Eve Van Cauter, PhD, the Frederick H. Rawson Professor of Medicine and director of the sleep, metabolism and health center at the University of Chicago.
"In this small but thorough study, however, we found that seven out of seven subjects had a significant change in insulin sensitivity. They are not tolerating the metabolic consequences," Cauter added.
Witnessing the direct effect of sleep deprivation on a peripheral tissue such as fat at the cellular level "was an eye-opener," said sleep-research graduate student, Josiane Broussard, PhD '10, lead author of the study.
It helps cement the link between sleep and diabetes and "suggests that we could use sleep like diet and exercise to prevent or treat this common disease," the researcher added.
The finding was published in the latest issue of the Annals of Internal Medicine.