According to lead researcher Xianchen Liu and his colleagues, in just 30 years the obesity rate has tripled among children aged 6 to 11 years, with about 17 percent of U.S. adolescents becoming overweight or obese.
An imbalance between calorie intake and energy expenditure from physical activity, has been known to lead to obesity. Other factors affecting the balance have however not been observed.
Liu, M.D., Ph.D., of the University of Pittsburgh School of Medicine Department of Psychiatry and Western Psychiatric Institute and Clinic of the University of Pittsburgh Medical Centre, and colleagues, conducted a number of studies on 335 children and adolescents age 7 to 17 years (average age 10.8).
Their studies discovered that there is an association between fewer hours of sleep and higher body mass index (BMI) in both adults and children.
A study of the participants' sleep pattern was monitored through polysomnography, for three consecutive nights. Their total sleep time was assessed, time spent in REM, the time it took them to fall asleep and other variables. Their weight and height were measured to calculate BMI.
It was discovered that a total of 49 participants (14.6 percent) were at risk of becoming overweight and 45 (13.4 percent) were overweight.
When a comparison was made with children with a normal weight, it was found that those who were overweight slept about 22 minutes less per night.
They also had lower sleep efficiency (percentage of time in bed that an individual is asleep), shorter REM sleep, less eye activity during REM sleep and a longer wait before the first REM period.
After taking into consideration the other related factors, one hour less of total sleep was associated with two-fold increased odds of being overweight and one hour less of REM sleep was associated with three-fold increased odds.
"Although the precise mechanisms are currently under investigation, the association between short sleep duration and overweight may be attributed to the interaction of behavioural and biological changes as a result of sleep deprivation," the authors write.
Sleep loss causes changes in hormone levels that may affect hunger, and also provides an individual with more waking hours in which to eat. In addition, sleep loss contributes to fatigue the following day, which may decrease physical activity and calorie expenditure.
"Given the fact that the prevalence of overweight among children and adolescents continues to increase and chronic sleep insufficiency becomes more prevalent in modern society, family- and school-based sleep interventions that aim to enhance sleep hygiene and increase sleep duration may have important public health implications for the prevention and intervention of obesity and type 2 diabetes in children," the authors conclude.
"Furthermore, our results demonstrate an important relationship between REM sleep and high BMI and obesity, suggesting that the short sleep-obesity association may be attributed to reduced REM sleep time and decreased activity during REM sleep," the authors concluded.
The report has been published in the August issue of Archives of General Psychiatry, one of the JAMA/Archives journals.