Molecular ties between lack of sleep and weight gain

NIH | APRIL 7, 2016

A poor night’s sleep can leave you feeling foggy and drowsy throughout the day. Sleep deprivation has also been associated with higher risks of weight gain and obesity.

Flaming June, by Frederic Lord Leighton (1830-1896), oil on canvas.

The researchers from the University of Chicago noticed that sleep deprivation has effects in the body similar to activation of the endocannabinoid (eCB) system, a key player in the brain’s regulation of appetite and energy levels. The eCB system affects the brain’s motivation and reward circuits and can spark a desire for tasty foods.

The participants to the study were placed on a fixed diet and allowed either a normal 8.5 hours of sleep or a restricted 4.5 hours of sleep for 4 consecutive days. For both conditions, the researchers collected blood samples from the participants beginning the afternoon following the second night.

When sleep-deprived, participants had eCB levels in the afternoons that were both higher and lasted longer than when they’d had a full night’s rest. This occurred around the same time that they reported increases in hunger and appetite.

After dinner on the fourth night, the participants fasted until the next afternoon. They were then allowed to choose their own meals and snacks for the rest of the day. All food was prepared and served in the clinical setting.

Under both sleep conditions, people consumed about 90% of their daily calories at their first meal. But when sleep-deprived, they consumed more and unhealthier snacks in between meals. This is when eCB levels were at their highest, suggesting that eCBs were driving hedonic, or pleasurable, eating.

Additional studies are needed to look at how changes in eCB levels and timing are affected by other cues, such as the body’s internal clock or meal schedules.

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