A trend for children and adolescents to stay up later and sleep less may be
linked to rising levels of obesity, according to a review of existing research
published on Thursday.
Bristol University researcher Shahad Taheri said televisions, computers,
mobile phones and other gadgets should be banned from children's bedrooms to
enable them to get a good night's sleep.
Writing in the journal Archives of Disease in Childhood, Taheri said there
was increasing evidence that shortened sleeping times result in metabolic
changes that may contribute to obesity, insulin resistance, diabetes and heart
disease.
A UK study published last year indicated that insufficient sleep in infants
aged 30 months was associated with obesity by the time they reached the age of
seven.
Taheri said this suggested that sleep loss at a young age may alter the
body's mechanisms that regulate appetite and energy expenditure.
Limited sleep is also a problem for teenagers, whose need for sleep increases
during the critical years of adolescent development.
Other research, published by Taheri in 2004, found that adults sleeping only
five hours had almost 15 percent higher levels of ghrelin -- a hormone released
by the stomach to signal hunger -- than those managing eight hours.
The same group of short sleepers also had more than 15 percent less Leptin, a
hormone produced by fat tissue when energy levels are low.
Children waking up tired from not enough sleep were also likely to take less
physical exercise, adding to the likelihood of putting on weight, Taheri said.
They would miss the beneficial effects of physical activity, not least its
tendency to lead to better sleep.
"Sleep is probably not the only answer to the obesity pandemic," Taheri said.
"But its effect should be taken seriously, as even small changes in energy
balance are beneficial."
He said children should observe regular sleeping and waking times, avoid
large meals at bedtimes and have a quiet dark bedroom that was neither too hot
nor cold.
Adolescents should be allowed to sleep in longer at weekends, but no more
than two to three hours beyond normal waking time, as this disrupts the body's
internal clock.
