Does losing sleep really make you overeat?

We’ve all missed a good night’s sleep at one time or another, so we know first hand how important sleep is. Chronic lack of sleep is a bigger issue, it can make us moody and anxious, it reduces mental acuity, and it’s associated with increased likelihood of several diseases – such as viral infections, diabetes and heart disease.

Insufficient sleep is also associated with weight gain and overeating. 

A recent meta-analysis including 11 interventional studies – in which people with partial sleep deprivation were compared to controls who slept normally – found that shortened sleep is associated with eating an extra 385 calories.

Lack of sleep is now considered an established risk factor for childhood obesity, even though the data is mostly observational. An analysis of seven studies, including 14738 participants finds that from infancy into adolescence, sleeping less is linked with the development of obesity.

Sleep and weight gain are linked, but that doesn’t explain how one affects the other. What is it about sleeplessness that triggers weight gain? 

It may be that the lack of sleep activates hunger through a cascade of hormones. Lack of sleep may also just move people to eat in the absence of hunger – an emotional kind of eating that has more to do with comfort or mindlessness, not with real hunger urges.   

Not hungry, still eating

A new study in the American Journal of Clinical Nutrition including 105 kids aged 8-12 looks at what sleep deprivation does to eating in the absence of hunger, ie: eating for the sake of eating.

The kids, who all had normal sleep (8-11 hours a night), were assigned to 2 weeks of sleep restriction in which they went to bed one hour later, and the same kids were also tested with 2 weeks of sleep extension, in which they went to bed one hour earlier, the sleep settings done in random order. On the last day of each week the kids were given a buffet style meal, and told to eat until they were full. After a 15 minute break the kids were asked back into the dining room and given a free range of things like ice cream, chips, cookies and chocolate. Each kid’s consumption was measured in both the meal and the after meal by weighing what’s missing from the serving plates.

The authors found that the kids – who are basically compared to themselves – didn’t increase caloric intake when they lost an hour of sleep compared to when they gained one. What they did find is that after the first meal experiment the kids lowered their consumption during the first course, leaving more room for the dessert session for the remaining 3 weeks of their experiment. In other words, the kids learned that there’s sweet and salty stuff coming later, and adjusted accordingly.

When the researchers looked at all the kids together, after just the first week, before kids could learn that dessert was coming, they found that the mild sleep deprivation did increase the eating-while-not-hungry intake by a little, but the study sample wasn’t big enough to prove this point.

In this respect, this experimental model failed to prove that sleep deprivation leads to a greater tendency of eating while not hungry.

Eating while sleep deprived

This is, however, just the way science moves on. The observational data finds that sleep deprivation is clearly linked with overeating. Designing and implementing randomized controlled studies and manipulating sleep to further understand the mechanism and to establish causality is still needed, and obviously challenging. And we can never completely control for biases such as screen time and socioeconomic factors even though the statistical models take those into account. Questions remain.

But we can already say with some confidence that chronic sleeplessness is a common trigger for overeating.

It may simply be that being awake longer gives us more time to engage in our favorite activity.

And being tired may also make us more susceptible to the temptations of the kinds of foods that make us overeat: fast and energy dense ones – tired people aren’t likely to chop kale and dress it in lemon juice in the middle of the night.

Solving sleep isn’t easy, but being aware of the connection between sleep deprivation and overeating can make us a little more mindful of what we do when we don’t get enough sleep.

Dr. Ayala