THURSDAY, Dec. 1 (HealthDay News) -- A new study suggests
regular physical activity might encourage better shut-eye: People
who met national exercise guidelines reported better sleep and less
daytime fatigue than those who didn't.
The research doesn't confirm that exercise directly leads to
improved rest, and it's possible there may be another explanation
for the apparent connection between exercise and sleep. Still, the
findings are mostly consistent with previous research, said Matthew
P. Buman, an assistant professor of exercise and wellness at
Arizona State University who's familiar with the study.
But if you think a daily walk or jog will clear up your sleep
problems, that might be a bit too optimistic.
"In general, the relationship between physical activity and sleep is moderate," Buman said.
More than one-third of U.S. adults have trouble falling asleep
at night or staying alert during the day, according to background
information in the study. Inadequate sleep has been linked to
depression, cardiovascular disease and other health problems.
The new study, led by researchers at Oregon State University,
looked at statistics from a U.S. health survey conducted from 2005
to 2006. The researchers focused on more than 2,600 men and women
-- aged 18 to 85 -- who measured their activity levels and answered
questions about sleep.
All wore accelerometers, devices that measure physical activity,
for a week.
The researchers adjusted their statistics so they wouldn't be
thrown off by unusually high or low numbers of people of certain
ages, weight, health condition, smoking history or other
The researchers then determined how many participants met or
exceeded national exercise guidelines by getting at least 150
minutes a week of moderate exercise or 75 minutes a week of
vigorous exercise or a combination of both.
Those who met the guidelines were 65 percent less likely to
report often feeling sleepy during the day compared to those who
got less exercise. They were also 68 percent less likely to report
sometimes having leg cramps and 45 percent less likely to report
having trouble concentrating while tired.
The study appears in the December issue of the journal
Mental Health and Physical Activity.
Buman called the finding intriguing, even if it doesn't prove
that exercise improves sleep.
If that is the case, however, the causes are unclear. Some
researchers think physical activity improves sleep by helping
reduce levels of stress, anxiety and depression, he said. "Others
have suggested an energy conservation hypothesis, essentially
saying that when you burn more calories through exercise, your body
more efficiently uses the sleep period to recover. Others have
suggested that exercise can modestly reduce body weight, which in
turn helps people to sleep better."
Another theory suggests that exercise helps the body deal better
with the cooling down of its temperature during sleep, he said.
So should you avoid exercising before bed, as conventional
wisdom suggests? The new research doesn't look at the timing of
exercise, but the study authors do note that most previous studies
haven't shown that late-night exercise disrupts sleep quality.
Study co-author Brad Cardinal, a professor of exercise science
at Oregon State, said in a statement that the study is unusual
because it directly measured how much exercise people got instead
of relying on their memories, which can be faulty.
The U.S. National Library of Medicine has details on