Can adding sleep subtract pounds?

Many studies have shown that kids and adults who sleep less are more likely to be overweight or obese. This correlation doesn’t prove that sleeplessness causes obesity: Obesity can lead to sleep problems, and lack of sleep might be associated with socioeconomic factors, less organized homes and other factors that affect weight gain.

But a new experimental sleep study, reported in Pediatrics, actually looked at what adding and subtracting sleep did to weight and caloric intake in kids, and its findings suggest that just changing sleep duration may impact kids’ waistlines.

The less you sleep, the more you eat

The researchers asked 37 kids, aged 8-11 years, 27 percent of them overweight or obese, to sleep as usual for the first week of the study. During the second and third weeks the kids alternated between sleeping 1½ hour more and 1½ hour less per night for an entire week. Sleep duration was verified by an actigraph – a device that is placed on the wrist and monitors activity level. On average, the actual sleep difference between the week with increased and decreased sleep was about 2½ hours.

So what can 2½ hours do?  During the week the kids slept more they reported eating 134 fewer calories per day compared to their intake during the reduced sleep condition, and their measured weight was about half a pound less.

While you may frown upon the 134-calorie decrease, if such a reduction is maintained over a long period of time – something further studies that last longer than 3 weeks will need to prove – this would be enormous. Weight is usually gained slowly, by eating just a little more than necessary over long periods of time. The energy gap is the daily discrepancy between energy intake and energy expenditure, and for American kids, the average energy gap estimate is just 64 calories a day. Eliminating calories in just the double digits daily could prevent further weight gain and doing that in your sleep could be sweet!

The exact mechanism in which sleep affects weight is unclear. After a good night’s sleep we might be more active and burn more calories, we might have reduced appetites, and craving for high-calorie foods might be curbed.

Getting a good night’s sleep

Getting enough sleep helps kids grow, concentrate in school, feel good, and – as this study further confirms -- keep a healthy weight.

And while getting enough sleep isn’t always easy, one of the factors that affect sleep is in our hands. TV before bed has been shown time and time again to result in kids sleeping later, and having a screen in the bedroom not only reduces sleep – it is correlates independently with overweight. 

Dr. Ayala