BEIJING, Feb. 8 (Xinhuanet) -- Enough sleep
might be an important way to fight against childhood obesity, the media
quoted researchers from the Northwestern University, Illinois,
U.S. as saying Thursday.
The researchers found in the study that children
who got more sleep tended to have a lower body mass index (BMI, a ratio of
weight to height) and were less likely to be overweight five years later, than
kids who got less sleep.
Emily Snell, a graduate student in human development
and social policy and colleagues at the Northwestern University tracked 2,281
children for five years starting from 1997 and also used detailed diaries
kept by families to examine children's sleep behavior and its relationship with
weight.
In the diaries the number of hours the children slept
was recorded, along with when they went to bed and what time they woke up. Their
height and weight were also logged.
"Children who get less sleep tend to weigh more five
years later," Snell said. One extra hour of sleep per night cut the likelihood
of being overweight from 36 to 30 percent in children aged 3 to 8, and from 34
to 30 percent in those aged 8 to 13.
Some researchers believe that teenagers simply cannot
get enough sleep because their bodies are biologically programmed to feel sleepy
later at night, while their school day is fixed to begin in early morning.
"Parents should be encouraged to put their younger
children to bed early enough so they can sleep at least 10 or 11 hours a night,"
Snell and colleagues concluded. "For older children, however, only later wake
times were associated with lower rates of overweight. This result supports
findings from the growing sleep literature encouraging later school start times,
particularly for adolescents," they added.
Sleep experts recommend that children aged 5 to 12
sleep for 10 to 11 hours a night and adolescents sleep for 8 to 9 hours. But
according to the research, children at age 7 on average got less than 10
hours of sleep on weekdays and at age 14, 8.5 hours.
(Agencies)
