You Snooze, You Lose: How Sleep Affects Your Weight

Source: Sleep Medicine Reviews (2007) 11, 163–178

It’s ten past 8am, you’ve been snoozing since 7:30 and didn’t get home until 3am or maybe you’ve been tossing and turning all night since 11pm. You decide to skip breakfast and later reach for chips, candy bars, and sugary and greasy snacks from the vending machine that you otherwise wouldn’t have. You end up feeling groggy and bloated and uncomfortable the whole day and throwing any plans to exercise out the window. If you’ve experienced any form of this, you’re one of many and there is a biological reason behind it.

Sleep disturbance or deprivation interferes with important metabolic processes.  Sleep deprivation can lead to weight gain because of changes in hormone levels that regulate appetite. Ghrelin, a hormone that signals hunger, increases with sleep deprivation. Conversely, the hormone leptin that signals fullness decreases. During sleep, the body secretes growth hormone which helps metabolize fat and regulate blood sugar. Its counter-hormone, cortisol, is a stress hormone that makes the body store fat and glucose. When sleep is disturbed, these hormones become imbalanced and the body favors cortisol, while limiting growth hormone.

A study examined the effect of sleep on metabolic parameters that detect the risk of obesity and diabetes. Subjects were fed an identical diet and underwent a phase of sleep deprivation (4 hours of sleep a night) for 6 days followed by an equal phase of extended sleep (12 hours of sleep a night) for recovery. During the deprivation phase, the results of their glucose tolerance test (a marker of type 2 diabetes) were 40% lower than the sleep recovery phase. Some of the subject’s glucose tolerance levels were so low that it resembled those of populations with a high risk of type 2 diabetes.  A similar study confirmed these findings and also found that the sleep deprived group also experienced a decrease in leptin levels and an increase in ghrelin.

Large population studies done around the world found a trend of longer sleep duration with a lower body mass index (BMI), the relationship between height and weight; however, many of these studies relied on self-reporting, which is not the most reliable tool.

You don’t have to be chronically sleep deprived for this to happen either. Even a sleep debt of two hours a night for a week can pose a risk for your health and increase your chances of glucose intolerance as well as weight gain.

After taking in account the different variables, one study in the US found that every extra hour of sleep is correlated with an 80% reduction in obesity risk.

How to get a good night’s sleep defined as at least 7 continuous hours, but preferably 8-9 hours:

• Get to bed early
• Drink chamomile or similar decaffeinated herbal teas before bedtime
• Turn off all noisy electronics and lights when going to sleep
• Try not to drink coffee or highly caffeinated beverages after noon