When you’re feeling run down, do you find yourself reaching for the cookie jar, or digging into a bag of potato chips? At the end of a long and tiring day, are you more likely to dig into a big bowl of ice cream, or help yourself to a second (or third) helping of takeout?
According to the latest research, your lack of sleep – and your sleep-deprived brain – may be fueling your junk food habit. Two separate studies investigated the relationship between insufficient sleep and the ability to make healthy food choices. And both studies arrived at the same basic conclusion: Lack of sleep hinders our ability to make smart choices about food, by causing changes to the way our brains function in areas of impulse control and decision-making.
Researchers at University of California Berkeley set out to investigate whether particular regions of the brain that we use to manage and regulate our food choices would be affected by a lack of sleep. Their study included 23 adults who were given brain scans on two separate occasions. The first occurred after a full night of sleep. The second took place after a night of less than adequate sleep. At the same time the MRI scans were being conducted, participants were asked to rate their desire for 80 different food items. Researchers found that activity in the brain’s frontal lobe was diminished after a poor night of sleep.
This region of the brain, which governs impulse control, judgment, emotional responses, and complex decision-making, plays an important role in food-related decisions.
Interestingly, researchers found no significant changes to the regions of the brain that govern basic desire. This indicates that sleep may be affecting our ability to make reasonable, healthy decisions about what foods to eat, rather than causing us to crave healthy foods more intensely when we’re tired.
In the second study, New York’s St. Luke’s-Roosevelt Hospital Center and Columbia University also used MRI scans to investigate the effects of reduced sleep on regions of the brain that help govern our food choices. In their study, 25 men and women were given brain scans after 5 nights of restricted sleep, when they slept no more than 4 hours per night. They were also given scans after 5 nights of normal sleep, which included as much as 9 hours of sleep per night. Similar to the previous study, participants were shown images of different foods – some healthy, some unhealthy –while undergoing MRI scans.
Researchers found that when people were short on sleep, exposure to images of unhealthy foods activated reward centers in the brain that were not activated by healthy foods. This reward-activation brain response only occurred when people were sleep deprived. There was no similar spike in reward-based brain activity when participants saw images of unhealthy foods after a full night of sleep.
We’ve known for some time that there is a powerful connection between sleep and weight. Getting enough sleep (but not too much!) on a regular basis helps keep weight under control over the long term. Not getting enough sleep, on the other hand, can make gaining weight all too easy:
- Sleep deprivation leads to greater overall calorie consumption, and a tendency to eat high-fat and high-sugar foods.
- Lack of sleep causes hormonal changes in the body that lead to increased appetite. Low sleep also deprives the body of REM sleep, which is not only restorative, it’s also a time when the body burns more calories than during any other stage of sleep.
- Sleeping too little can cause people to eat later and to eat more of their total calories at night, which contributes to weight gain.
These most recent studies provide another important piece of the sleep-weight puzzle, by showing us how our basic ability to make smart food choices can be affected by the amount of sleep we get. Our ability to use good judgment when making food choices is compromised when we’re short on sleep – and according to these studies, that’s not a matter of “willpower.” Rather, our brain function is altered when we’re sleep deprived, in ways that make choosing a piece of fruit over a slice of cake a whole lot more difficult.
Whether you’re looking to lose weight or to maintain a healthy weight, keep in mind that a good night’s sleep can be a powerful weapon in your ability to resist the foods that can derail a healthy diet.
Michael J. Breus, PhD
The Sleep Doctor™