Women who go to bed and wake up at regular times tend to maintain a healthy weight, a new study suggests.
Research has shown that not sleeping
enough can have an effect on weight, but this new study from Brigham
Young University finds that consistency in sleeping times can influence
"The message of this study seems fairly straightforward: Sleeping well
consistently is associated with lower body fat in young women," said
Dr. David Katz, director of the Yale University Prevention Research
Center. Katz was not involved with the study.
The study also
suggested that better sleep -- characterised by its efficiency,
consistency and duration -- is associated with more routine physical
activity, he said.
Good sleepers are 'healthier'
of the advantage in body composition from better sleep appears to be
the effect of sleep itself, while some may be a product of more
activity, " Katz said. "It may also be that exercise facilitates better sleep, or vice versa."
Katz cautioned, however, that this study did not prove a cause-and-effect relationship between sleep and weight.
The report was published online in the American Journal of Health Promotion.
the study, a team lead by exercise science expert Bruce Bailey
collected data on 330 college women. Over a weeklong period, those who
slept and woke at consistent times maintained a healthier weight.
who went to bed and woke up at or around the same time each day had
lower body fat. Those who slept between eight and eight and a half hours
had the lowest body fat, the researchers found.
Those whose sleep patterns varied more than 90 minutes had higher body fat than those whose sleep patterns varied less than 60 minutes, the researchers found.
Too much sleep not good either
too little or too much sleep also had an effect on body fat. Sleeping
less than six and a half or more than eight and a half hours a night was
associated with higher body fat.
Moreover, quality of sleep was important, with those who had better sleep quality having lower body fat, the researchers found.
quality is a measure of how much time spent in bed is spent sleeping.
Bailey said staying up late or sleeping in may be doing more harm than
"We have these internal clocks, and throwing them off and
not allowing them to get into a pattern does have an impact on the
[physical and chemical functioning of our bodies]," Bailey said in a
Consistent sleep patterns are good sleep hygiene, he
said. When sleep is changed, it can change physical-activity patterns
and affect some hormones involved with metabolism and contribute to
excess body fat, Bailey said.
To improve sleep quality, Bailey
recommends exercising, using beds only for sleeping, and keeping the
bedroom cool, quiet and dark.
Katz said more research is needed
since the findings are specific to young women. "But there is no
apparent reason why they would not pertain equally to men," he said.
"For now, it is reasonable to reaffirm that sleep matters to weight control and health," Katz said.
Visit the National Sleep Foundation for tips on how to improve your sleep habits.