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 Researchers found that a night of restricted sleep was followed by
extended peaks, later in the day, in natural signaling chemicals
that regulate hunger and pleasure. They think that may be one reason
sleep deprivation is linked to weight gain.
“Our current study adds to that growing literature and suggests that
along with changes in leptin and ghrelin, alterations in
endocannabinoids - all changing in the direction to favor food
intake - may be mechanisms by which sleep restriction promotes
overeating,” said lead author Erin Hanlon, a research associate in
endocrinology, diabetes and metabolism at the University of Chicago.
“And, on a larger scale, evidence from both laboratory and
epidemiologic studies have consistently associated insufficient
sleep or short sleep with increased risk of obesity,” Hanlon said.
The researchers studied 14 healthy young adults ranging in age from
18 to 30 years who got four nights of sufficient sleep, about eight
and a half hours, then four nights of sleep restricted to 4.5 hours.
The two sleep tests took place in a sleep lab and were separated by
a month.
During waking hours, participants were housed in a private room and
kept basically sedentary. They had three identical meals at 9 a.m.,
2 p.m. and 7 p.m.
In each test, calorie intake was controlled for the first three days
and on the fourth day participants were allowed to eat as much or as
little as they liked from a buffet tailored to individual
preferences. Meanwhile, researchers monitored participants' calorie
intake and analyzed blood samples.
Participants also answered questions about their hunger, appetite,
energy level and mood during the 24-hour period of blood sampling,
25 minutes before each meal and one hour and 35 minutes afterward.
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But in the sleep-deprived phase, 2-AG remained elevated late in the
evening and participants reported higher hunger scores, according to
the results in the journal Sleep.
“These are the first results showing that sleep restriction
influences the endocannabinoid system in humans,” said Frank Scheer
of the Medical Chronobiology Program at Brigham and Women's Hospital
in Boston who wrote a commentary alongside the new study. “This
opens up a new insight into systems involved in energy balance and
food reward,” he told Reuters Health by email.
“Previous studies had shown that experimental sleep loss causes an
increase in ‘hunger hormone’ ghrelin and a decrease in ‘satiety
hormone’ leptin,” Scheer said. “The increase in the peak in
endocannabinoids following sleep restriction provides an additional
mechanism that could help explain an increase in hunger.”
Adults should aim for seven to nine hours of sleep per night, he
said.
“With decreasing amounts of sleep, the metabolic effects appear to
become progressively stronger,” Scheer said.
SOURCE: http://bit.ly/1UzIW0G and http://bit.ly/1VRhaLB Sleep,
online February 29, 2016.
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