Does lack of sleep cause weight gain?
Thanks to Walter Vandereycken for drawing my attention to an interesting article which is written by Patricia Prinz and is free to download from an open access journal 'Public Library of Science: Medicine'.
The article deals with the increasing evidence suggesting that getting less than 8 hours sleep per night may be associated with weight gain and put people at risk of obesity. The largest of the studies mentioned included 1.1 million participants so it seems to be a robust finding! Another recent study was prospective in design, which meant that people were followed over time to see how lack of sleep was related to future weight gain. This clarifies the question about the direction of causation - data from earlier cross-sectional studies could have been due to obesity leading to poor sleep rather than the other way round.
The mechanism behind the relationship between lack of sleep and weight gain is not yet fully understood. However Prinz's article implicates two metabolic hormones, ghrelin and leptin, in the process. Ghrelin is involved in appetite and in sleep regulation, and one suggestion is that lack of sleep leads to the production of increased amounts of ghrelin, in order to increase sleepiness, but that this has the unfortunate side effect of increasing appetite, leading to overconsumption of food.
Good night, sleep tight!
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