Last month I reported on a study which linked shorter sleep duration with an increased risk of diabetes. Other research has found an association between relatively curtailed sleep and an increased risk of overweight and obesity. Some of this research has found a potential explanation for this observation in the form of changes in appetite regulating hormones such as leptin and ghrelin. Lower levels of the appetite quelling leptin and/or higher levels of the appetite stimulating ghrelin as a result of curtailed sleep might increase food intake and predispose to overweight and obesity.
In a recent study published in the American Journal of Clinical Nutrition , the effect of sleep duration on leptin and ghrelin levels was assessed. 11 adults were assessed for over two, fortnight-long periods. During one spell, they were restricted to 5.5 hours of sleep a night. During the other, the prescribed nightly sleep time was 8.5 hours. This study found no difference in the levels of ghrelin or leptin between the two sleep conditions.
However, food intake did differ between the two groups. The primary difference here was that during the shorter sleep phase, individuals ate an average of about 200 calories more each day. This additional consumption did not come during meal time, but as snacks. Not only that, but shorter sleep time was associated an increase in the number of calories coming from carbohydrate: 61 per cent of calories came from carbohydrate during the longer sleep phase, which increased to 64 per cent when sleep was curtailed.
The authors of this study concluded, Recurrent bedtime restriction can modify the amount, composition, and distribution of human food intake, and sleeping short hours in an obesity-promoting environment may facilitate the excessive consumption of energy from snacks but not meals. The message from this study appears to be that if we want to keep our food intake in check, it may well help to make sure we get a decent amount of sleep each night.
1. Nedeltcheva AV, et al. Sleep curtailment is accompanied by increased intake of calories from snacks. Am J Clin Nutr. 2009;89(1):126-33.