睡眠充足有利于保持好身材
(2008-05-05 09:28:21)
An extra hour between the sheets at night might be the key to
shedding excess weight and fighting obesity, according to recent
research.
"More sleep
could be the ideal way of stabilizing weight or slimming," said
neuro-scientist Karine Spiegel, of France's INSERM, a public
organization dedicated to biological, medical and public health
research.
While poor
eating habits and lack of exercise clearly play a role in the
global rise of obesity, recent data indicates that lack of sleep
may also be a factor, and one that is often under-estimated.
Around 30
surveys carried out on wide population samples in seven countries
have underlined a link between lack of sleep and excess weight or
obesity in both children and adults, Spiegel said.
The first of
the studies, carried out in 1992 in France, highlighted the problem
in children and teenagers. Spiegel said the increase in obesity in
the US in the second half of the 20th century corresponded with a
mounting decrease in sleep.
Two key
hormones produced at night which help regulate appetite were at
play, she said.
Grehlin
makes people hungry, slows metabolism and decreases the body's
ability to burn body fat, and leptin瘦素, a protein hormone
produced by fatty tissue, regulates fat storage.
"We have
shown that less sleep (two four-hour nights) caused an 18 percent
loss of appetite-cutting leptin and a 28 percent increase of
appetite-causing grehlin," she said.
Such
hormonal changes made people hungry for foods heavy in fats and
sugars such as chips, biscuits, cakes and peanuts, she added.
The sleep
loss caused a 23 to 24 percent increase in hunger, Spiegel said,
translating into an extra 350 to 500 kilocalories a day, "which for
a young sedentary adult of normal weight could lead to a major
amount of added weight."
It was
unclear whether several years of sleep deprivation could lastingly
harm the body's ability to restore a balance between the two
hormones.
A study
released in Washington in February showed children lacking shut-eye
faced a greater risk of becoming obese than kids who got a good
night's sleep.
Each extra
hour of sleep cuts a child's risk of becoming overweight or obese
by nine percent, according to an analysis of epidemiological
studies by researchers from Johns Hopkins Bloomberg School of
Public Health.
By contrast,
children who got the least sleep had a 92 percent higher chance of
being overweight or obese than children who slept enough, said the
study published in the journal Obesity.
"Our
analysis of the data shows a clear association between sleep
duration and the risk for overweight or obesity in children. The
risk declined with more sleep," said Youfa Wang, a senior author of
the study.
"Desirable
sleep behavior may be an important low cost means for preventing
childhood obesity and should be considered in future intervention
studies," Wang said in a news release.
The
researchers reviewed 17 published studies on sleep duration and
childhood obesity.
Some
research recommends that children under five years old sleep 11
hours or more a day, while children age five to 10 should get 10 or
more hours of sleep, and children older than 10 should sleep at
least nine hours.
Vocabulary:
metabolism：新陈代谢
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