Poor sleep provokes junk food cravings, U.S. study finds

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Poor sleep provokes junk food cravings, U.S. study finds

Fruit and vegetable companies might want to encourage better sleeping habits amongst the public, as sleepless nights give their competitors an edge. Junk food shot ebru Flickr

Following on from a UC Berkeley study conducted in 2013, a recent paper published in the journal SLEEP digs deeper into why we are quicker to consumer junk food when sleep-deprived.

The study found sleep loss led to a mechanism that mimicked the marijuana 'munchies', amplifying and extending blood levels of a chemical signal that enhances the joy of eating, particularly the guilty pleasures gained from sweet or salty, high-fat snack foods.

Sleep-deprived participants who were all young and healthy volunteers were reportedly unable to resist what the researchers called "highly palatable, rewarding snacks", meaning cookies, candy and chips, even though they had consumed a meal that supplied 90% of their daily caloric needs two hours before.

The effects of sleep loss on appetite were most powerful in the late afternoon and early evening, times when snacking has been linked to weight gain.

"We found that sleep restriction boosts a signal that may increase the hedonic aspect of food intake, the pleasure and satisfaction gained from eating," said Erin Hanlon, PhD, a research associate in endocrinology, diabetes and metabolism at the University of Chicago.

"Sleep restriction seems to augment the endocannabinoid system, the same system targeted by the active ingredient of marijuana, to enhance the desire for food intake."

This chemical signal is the endocannabinoid 2-arachidonoylglycerol (2-AG). Blood levels of 2-AG are typically low overnight. They slowly rise during the day, peaking in the early afternoon.

When the study subjects were sleep-deprived, however, endocannabinoid levels rose higher and remained elevated through the evening, beyond the typical 12:30 p.m. peak.

During that period, sleep-restricted study subjects reported higher scores for hunger and stronger desire to eat. When given access to snacks, they ate nearly twice as much fat as when they had slept for eight hours.

"The energy costs of staying awake a few extra hours seem to be modest," explained Hanlon.

"One study has reported that each added hour of wakefulness uses about 17 extra calories. That adds up to about 70 calories for the four hours of lost sleep.

"But, given the opportunity, the subjects in this study more than made up for it by bingeing on snacks, taking in more than 300 extra calories. Over time, that can cause significant weight gain."

The research was supported by the National Center for Research Resources, the Department of Defense, the Medical College of Wisconsin and the University of Chicago Institute for Translational Medicine.

Photo: ebru - Flickr


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