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Sleep Duration Affects Appetite-Regulating Hormones
Published: December 7, 2004
Copyright: © 2004 Public Library of Science. This is an open-access
article distributed under the terms of the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction
in any medium, provided the original work is properly cited.
Some of us, when awake in the middle of the night, feel an urge to
visit the kitchen. This could explain results of previous studies
that have shown a link between short sleep duration and high body
mass index (BMI). But a study by Emmanuel Mignot and colleagues suggests
that it's not just the additional snacking opportunities that make
short sleepers more likely to be overweight.
Intrigued by the connection between sleep and BMI, and by recent
studies showing that sleep deprivation in laboratory settings can
cause a decrease in serum levels of leptin, a hormone known to control
appetite, Emmanuel Mignot and colleagues set out to study the levels
of various hormones known to regulate appetite and energy expenditure
under “real life” conditions.
They took advantage of the Wisconsin Sleep Cohort Study, an ongoing
longitudinal study of sleep habits and disorders in the general population.
The study began in 1989, when researchers mailed state employees aged
30–60 years a survey on sleep habits, health, and demographics. Mail
surveys were repeated at 5-year intervals, and some of the respondents
were recruited to sleep a night in the laboratory and undergo various
tests. A number of participants were also asked to keep a sleep diary
for 6 days. The study has already shown connections between sleep
apnea and hypertension, and between menopause and sleep-disordered
breathing.
For their study, Mignot and colleagues measured sleep duration (habitual
and immediately prior to blood sampling), BMI, and pre-breakfast blood
hormone levels in 1,024 participants. Consistent with previous studies,
they found that in individuals who sleep less than 8 hours (74% of
all participants), BMI was inversely proportional to sleep duration.
In addition, short sleep was associated with low leptin and high ghrelin
levels (ghrelin is a hormone thought to stimulate food intake).These
hormonal differences are likely to increase appetite, which could
be responsible for the increased BMI in short sleepers.
These findings could explain, at least in part, why societies in
which excess calories are much easier to come by than a good night's
sleep are more prone to obesity. Mignot and colleagues plan to test
this in intervention studies where they make people sleep more and
measure the effects on body mass. “Good sleep, healthy eating habits,
and regular exercise each may have important roles in fighting obesity
in modern society,” suggests Mignot.
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