Junk Food Cravings Linked To a Lack of Sleep, Study Suggests

An anonymous reader quotes a report from The Guardian: Writing in the Journal of Neuroscience, Peters and colleagues describe how they recruited 32 healthy men aged between 19 and 33 and gave all of them the same dinner of pasta and veal, an apple and a strawberry yoghurt. Participants were then either sent home to bed wearing a sleep-tracking device, or kept awake in the laboratory all night with activities including parlor games. All returned the next morning to have their hunger and appetite rated, while 29 of the men had their levels of blood sugar measured, as well as levels of certain hormones linked to stress and appetite. Participants also took part in a game in which they were presented with pictures of 24 snack food items, such as chocolate bars, and 24 inedible items, including hats or mugs, and were first asked to rate how much they would be willing to pay for them on a scale. During a functional magnetic resonance imaging (fMRI) scan, they were asked to choose whether or not they would actually buy the object when its price was fixed -- an experiment that allowed researchers to look at participants' brain activity upon seeing pictures of food and other items. A week later, the experiment was repeated, with the participants who had previously stayed up allowed to sleep, and vice versa.

The results showed that whether sleep-deprived or not, participants were similarly hungry in the morning, and had similar levels of most hormones and blood sugar. However, when participants were sleep-deprived, they were willing to pay more for a food snack than when rested, and had higher levels in their blood of a substance called des-acyl ghrelin -- which is related to the 'hunger hormone' ghrelin, though its function is not clear. The fMRI results showed that when sleep-deprived, participants had greater activity in the brain's amygdala (where food rewards are processed) when food images were shown, and a stronger link between the price participants would pay for food and activity in the hypothalamus (which is involved in regulating consumption). Interactions between these two regions increased compared with when participants had slept.

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