The amount of time people spend sleeping
may affect their weight, study results suggest.
The study looked at
people living in rural areas. Previous studies
conducted in urban and suburban areas have
had similar results, which suggests that sleep
loss may play a role in the increasing rates
of obesity in the US.
Researchers have proposed that shorter sleep
duration may affect levels of two weight-control
hormones: reduced levels of leptin, a hormone
associated with satiety, and increased levels
of ghrelin, associated with hunger.
Dr. Neal D. Kohatsu, an epidemiologist at
the California Department of Health Services
in Sacramento, and his associates were interested
in studying rural populations because obesity
rates are higher and lifestyle patterns of
nutrition, physical activity, work hours,
and sleep differ from those in more populous
areas.
Rural populations also have a higher prevalence
of suicide and a greater propensity toward
other risky health behaviors.
According to the researchers' report in the
Archives of internal Medicine, theirs is the
first study evaluating the relationship between
sleep duration and body mass index (BMI) in
rural settings. BMI reflects weight in relation
to height, with 20-25 classified as normal,
25-30 as overweight, and over 30 as obese.
The team analyzed data collected in an agricultural
county in southeastern Iowa, from a survey
of a random sample of 990 employed adults.
The subjects were asked about sleep duration,
physical activity associated with employment,
symptoms of depression, alcohol consumption,
snoring, and other demographic information.
Height and weight were measured during the
same visit.
There was a straight-line relationship between
a higher BMI and lesser amount of sleep. The
average BMI ranged from 30.24 among individuals
sleeping less than 6 hours per night, to 28.25
for those who slept more than 9 hours at a
time.
Kohatsu's group speculates that "modest but
sustained changes in sleep duration could
have a clinically significant effect on weight."
They acknowledge, however, that the study
doesn't prove that reduced sleep causes obesity.
SOURCE: Archives of internal Medicine, September
18, 2006.
