October 16, 2012
Lack Of Sleep Disrupts Fat Cells’ Ability To Respond To Insulin
Brett Smith for redOrbit.com - Your Universe Online
While it is well-documented that a lack of sleep can make people irritable and unfocused, a new study from University of Chicago Medicine researchers shows that a lack of rest can also affect fat cells–making them 30 percent less responsive to insulin.
The study, published in the journal Annals of Internal Medicine, is the first to describe a molecular mechanism that is directly affected by sleep loss. This disruption of fat cells can then lead to additional adverse effects, according to researchers.
"We found that fat cells need sleep to function properly," said study author Matthew Brady, an associate professor of medicine at the University of Chicago. "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."
To study how sleep loss can affect metabolism, the team recruited seven healthy and active adults to live in a sleep laboratory for two, four-day periods. The volunteers were fed identical meals over this time period and had no access to snack foods.
During the first four-day period, the participants were asked to spend 8.5 hours a night in bed and slept an average of 7.9 hours. During the second session, they were asked to spend 4.5 hours a night in bed and slept an average of 4.4 hours–resulting in the loss of 14 hours of sleep over the course of 4 days.
At the end of each four-day session, participants´ response to insulin was tested. Fat tissue was also collected from each volunteer and tested for its response to insulin at the cellular level.
The results show the average response to insulin by participants´ bodies dropped by 16 percent after the sleep deprivation period. More alarmingly, the fat cells showed a 30 percent decrease in insulin response. The researchers noted that these results indicate a precursor to type-2 diabetes.
"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, a professor of medicine at the university.
“Some people claim they can tolerate the cognitive effects of routine sleep deprivation," said co-author Eve Van Cauter, another professor 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."
The researchers noted that their findings underline the need for people to get a good night´s sleep or make up for sleep loss whenever possible.
Van Cauter admits that individual sleep needs vary, with younger people requiring seven to nine hours and older folks needing slightly less. She recommends using vacation time to discover your personal sleep needs by shutting off any alarm clocks and calculating the average time your body sleeps over the course of several days.