WASHINGTON (AP) - Older women who often have trouble sleeping
may want to consider a little workout in the morning for a better
rest at night.
Morning exercisers had fewer complaints about a bad night's
sleep and those who stretched in the morning had somewhat better
sleep, a new study found. Women who exercise in the evening, on the
other hand, were more likely to be up at night.
The women didn't need much morning activity to get the benefit.
``It's like doing a brisk walk,'' said researcher Anne McTiernan.
``Nobody is saying people have to be athletes and do marathons.''
The scientists at Fred Hutchinson Cancer Research Center in
Seattle drew their data from a larger study of the effects of
exercise in reducing the risk of breast cancer. Because the study
included survey questions on sleep, the researchers could examine
an issue that was not part of the original project. McTiernan is
principal investigator of the cancer study as well as senior
researcher on the sleep project, whose findings were published in
the November issue of the journal Sleep.
Women in the sleep study were cancer-free and postmenopausal,
ages 50 to 75, overweight or obese, and not exercising at the start
of the project. Eighty-seven were placed in the exercise program
and 86 in the stretching program. Both groups were followed for a
year. Researchers compared how well the women reported sleeping
before the study started and afterward.
Women in the exercise program did at least 45 minutes of
moderate walking or riding an exercise bike five days a week at an
exercise facility or on their own. Those who were stretching did an
hour once a week under the supervision of an exercise physiologist,
and stretched 15 to 30 minutes three times a week on their own.
Fifty-five percent of all the women did their activity in the
morning.
Although the exercise program was about 15 minutes a day more
than federal officials recommend as the minimum for healthful
exercise, it's still not a lot, McTiernan said. The heart rates of
the exercisers were no higher than they would get in a brisk walk,
she said.
How the women did in their programs was compared with their
ratings of their ability to sleep, including whether they used
sleep aids such as pills or alcohol, whether they felt they were
sleeping soundly and through the night, and whether they fell
asleep during quiet activities.
Women who exercised averaged 70 percent better sleep and women
who stretched averaged 30 percent better sleep, the study found.
The study did not look for reasons why exercise in the morning
was good for a night's rest while exercise at night was not, or why
stretching would help at all.
The researchers suspect that exercise in the morning might set
the women's body clocks for a day of activity and a night of sleep,
while exercise at night might push back the sleep part of the
sleep-wake cycle. They speculate that the stretches might have
improved sleep by making the women more flexible and relaxed.
Exercise also increases activity hormones and creates lactic
acid as a byproduct, and both can make a body more restless, said
Edward Stepanski, director of the Sleep Disorders Service and
Research Center at Rush University Medical Center in Chicago.
Similarly, exercise raises temperature, while sleep requires a
slight drop in temperature, said Stepanski, who was not part of the
Fred Hutchinson study.
As for why exercise might be better in morning, Stepanski also
suspects a change in circadian rhythm. Finding out whether morning
exercise benefits the body clock would be an interesting follow-up
study, he said.
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On the Net:
Abstract of journal article:
http://www.journalsleep.org/citation/sleepdata.asp?citationid2280
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