Getting an adequate night’s rest of eight hours is a no-brainer for dieters. Studies have long shown that insufficient sleep spikes levels of stress hormone cortisol, and when the body is stressed, it holds on to excess weight. Now, new MRI research has shown that sleep deprivation affects an individual’s ability to maintain a healthy body weight even more so than was previously supposed: lack of sleep has actually been linked to powerful cravings for nutritionally empty high-calorie junk foods such as pizza and chips.
Researchers from UC Berkeley used fMRI imaging to scan the brains of 23 healthy young adults, first after a proper night’s sleep and second, after a sleepless night. Presented with both healthy and unhealthy food choices during each scan, participants overwhelmingly favoured junk foods following their all-nighters.
Why?
After a sleepless night, impaired function in the brain’s frontal lobe–the part of the brain that governs complex decision making relating to the long term–was observed, while the brain’s ‘reward centres’ showed increased activity. Says co-author of the study and UC psychology professor Matthew Walker, “What we have discovered is that high-level brain regions required for complex judgments and decisions become blunted by a lack of sleep, while more primal brain structures that control motivation and desire are amplified.”
Each participant was shown a series of 80 food images that ranged from nutritiously dense but low-calorie foods like strawberries and carrots to more processed foods like pizza and burgers–and each participant was offered the food they most wanted afterwards as an incentive–legitimizing the study’s cravings as urges that were acted upon.
Add ‘better self-control’ to the list of reasons why it makes sense to get a good night’s sleep.