The impact of sleep on childhood obesity

Researchers at WCM-Q have shown that lack of sleep is likely to be a contributing factor in childhood obesity in Qatar.

The relationship between obesity and insufficient sleep has been demonstrated before, but the majority of studies have relied on subjective estimates of sleep, and only one indicator of obesity.

By contrast, the team from WCM-Q used five indicators of obesity to ensure the condition was accurately defined. They also issued each subject with a wrist actigraphy device which records movement and allows researchers to accurately and objectively estimate sleep parameters.

The study was conducted on 335 elementary schoolchildren in Qatar who were aged between seven and 12. Each child was asked to wear the actigraph for seven consecutive days and nights. The children had their neck and waist circumferences measured, their height and weight taken (allowing their body mass index [BMI]) to be calculated, and their percentage of body fat and fat mass measured.

The research found that the average time at which the children went to sleep during the week was 9.22pm, and the average time at which they woke was 6.26am.

Of the sample, 42.1 per cent were classified as either overweight or obese according to the definitions from the World Health Organization. Of those children, weekday sleep duration was significantly shorter at 7 hours 36 minutes, as opposed to 7 hours 54 minutes for those who were a healthy weight.

Although sleep is certainly not the only factor involved in obesity, the researchers state that it appears to be a contributory factor. Sleep duration may influence food intake, food selection, and energy expenditure with downstream effects on body fat.

Dr. Shahrad Taheri, director of the clinical research core and assistant dean for clinical investigations said that the body of evidence pointed to a lack of sleep having an effect on a person’s weight, and there is increasing evidence to support this from studies of both children and adults. 

Dr. Taheri added: “Here, we observe the relationship between sleep and obesity in the first study of sleep in schoolchildren in Qatar. The study demonstrates that conditions like obesity are far more complex than we first thought, and should be treated holistically. Qatar has a high prevalence of obesity and there is a need to look at improving sleep to prevent and tackle obesity. We plan to undertake further research to see if it is possible to reduce obesity through lifestyle change that includes diet, physical activity, and sleep”