October 15, 2012 -- Updated 2104 GMT (0504 HKT)
Fat cells become "metabolically groggy" in someone who is sleep-deprived, according to a new study.
STORY HIGHLIGHTS
- Sleep deprivation impairs fat cells' ability to respond to insulin, a study shows
- Insulin regulates metabolism and is involved in diabetes
- Lack of sleep may trigger the body's stress response
- The small study needs to be confirmed in different populations, settings
Scientists have come up
with a number of plausible explanations for this increased risk. Various
studies have shown, for instance, that how much we sleep can affect
blood sugar levels, hormones that control appetite, and even the brain's
perception of high-calorie foods.
A small new study,
published Monday in the Annals of Internal Medicine, adds a key piece
to the puzzle by drilling down to the cellular level: Sleep deprivation,
the study found, impairs the ability of fat cells to respond to
insulin, a hormone that regulates metabolism and is involved in
diabetes.
In the study, seven
healthy young men and women spent a total of eight days and nights in a
sleep lab. They were allowed to sleep normally on four of the nights,
and on the other nights they were limited to just 4.5 hours. In order to
neutralize the effects of appetite or overeating, the researchers
strictly controlled the participants' meals and calorie intake.
After the four nights of
sleep deprivation, blood tests revealed that the participants' overall
insulin sensitivity was 16% lower, on average, than after the nights of
normal sleep. Moreover, their fat cells' sensitivity to insulin dropped
by 30%, to levels typically seen in people who are obese or who have
diabetes.
"This is the equivalent
of metabolically aging someone 10 to 20 years just from four nights of
partial sleep restriction," says Matthew Brady, the senior author of the
study and an associate professor of medicine at the University of
Chicago. "Fat cells need sleep, and when they don't get enough sleep,
they become metabolically groggy."
Specifically, the
participants' fat cells -- which were collected via biopsy and analyzed
-- required nearly three times as much insulin to activate an enzyme
known as Akt, which plays a crucial role in regulating blood sugar. If
insulin resistance of this sort becomes persistent, excess sugar and
cholesterol can accumulate in the blood, increasing the risk of diabetes
and heart disease.
Previous sleep-lab
studies have found that insufficient sleep can affect overall insulin
sensitivity, but this is the first to identify a concrete cellular
mechanism that might underlie the well-established links between sleep,
diabetes and obesity.
"This takes the research
on the effect of sleep deprivation on metabolism one step further, by
revealing a molecular mechanism involved in the reduction of total body
insulin sensitivity," says Dr. Nathaniel F. Watson, co-director of the
University of Washington Medicine Sleep Center, in Seattle, who was not
involved in the study.
"If you want to make a
causal argument that short sleep is causing diabetes," Watson adds, "one
of the key elements is coming up with a physiological mechanism by
which this would happen."
Brady and his coauthors
aren't yet sure how exactly fat cells recognize and register sleep
deprivation. One possibility, they say, is that lack of sleep triggers
the body's stress response, leading to the release of the stress
hormones cortisol and norepinephrine, which are associated with insulin
resistance.
The new findings will
need to be confirmed in different populations and settings. The study
included only seven people (and just one woman), and they were all
young, healthy, and lean, so the results can't necessarily be
extrapolated to people who are older or overweight.
Likewise, the sleep
deprivation in the study was relatively drastic and short-lived. It's
unclear whether less severe sleep deprivation over longer periods of
time -- a more common real-world scenario -- would have the same effect
on fat cells.
If the results are borne
out in the future, the good news is that the treatment for the type of
insulin resistance seen in the study is straightforward: sleep more.
Sleep is "as important
to your health as a healthy diet and exercise," Watson says. "Until
somebody invents a procedure or a pill that's going to approximate all
aspects of sleep, really what you're left with is what is a pretty
simple treatment... Just turn off the computer and go to bed earlier."
Copyright Health Magazine 2011
No comments:
Post a Comment