Earlier this month I wrote about a study in which the effect of sleep deprivation on appetite ratings in response to images of food was tested [1]. Overall, subjective feelings of hunger were significantly greater after the night of sleep deprivation. The study subjects underwent brain scanning too (functional magnetic resonance imaging). After a night of sleep deprivation, there was enhanced activity in a part of the brain known as the anterior cingulate cortex – a structure which, among other things, influences our sense of appetite and hunger. This study appears to provide evidence that a lack of sleep might drive a tendency to overeat.
Hot on the heels of this study comes another in a similar vein [2]. In this study, 30 healthy men and women’s responses to pictures of food were tested with functional magnetic resonance imaging (fMRI) – a scanning test which allows us to see activity in different parts of the brain. The subjects were each tested in both of two settings:
1. after 6 nights of being allowed to spend 9 hours a night in bed (normal sleep)
2. after 6 nights of being allowed to spend 4 hours a night in bed (restricted sleep)
Overall, brain activity was higher during exposure to food images after restricted sleep. In particular, there was a relative increase in brain activity in areas associated with ‘reward’. This study provides more evidence that lack of sleep can drive a propensity to overeat.
There’s been a general trend for sleep times to reduce over time. It seems likely to me that this factor is contributing, at least some degree, to the burgeoning rates of obesity seen in industrialised countries.
References:
1. Benedict C, et al. Acute Sleep Deprivation Enhances the Brain’s Response to Hedonic Food Stimuli: An fMRI Study. J Clin Endocrinol Metab 2012 Jan 18. [Epub ahead of print]
2. St-Onge M-P, et al. Sleep restriction leads to increased activation of brain regions sensitive to food stimuli. Am J Clin Nutr 22 Feb 2012 [epub ahead of print]
