Can't figure out why you're gaining weight - or why it's so difficult to erase those extra pounds? You might be suffering from sleep deprivation... even if you swear you're getting enough sleep at night. In fact, one study found that just getting 30 fewer minutes of sleep than you should get per weekday can increase your risk of obesity and diabetes.
Logically, it's practically impossible to stay committed to a healthy lifestyle if you don't have the energy for it. "If I've gone to bed late or I have a restless night, I'm more likely to turn off my alarm in the morning and skip my workout. It could be me consciously thinking, 'No way am I going to that exercise class', or, unconsciously snoozing to the point that it's too late to make it to the class."
Most of us have been there before. But there are also scientific reasons why a lack of sleep can contribute to weight gain.
Sleep: You Body's Best Friend
If you thought under-eye circles were the worst consequence of skimping on sleep, you're in for a shock. "Sleep is important for pretty much every one of your physical systems," says Janet K. Kennedy, PhD, clinical psychologist and found of NYC Sleep Doctor. "Sleep deprivation leads to deficits in cognitive functioning, whether it's reaction time, decision-making, or memory."
Sleep is essential for beyond just what's going on in your brain, too. "Sleep is involved in the repair and restoration of the body. The rest that happens during sleep really rejuvenates your body for the next day," says Kennedy.
Plus, you might be suffering from the symptoms of sleep deprivation, even if you think you're spending enough time in the sack. "W
e used to think you needed a significant amount of sleep deprivation for it to have an effect on weight. It turns out that's not true," says Michael Breus, PhD, a sleep specialist and author of The Sleep Doctor's Diet Plan: Lose Weight Through Better Sleep. Just 30 minutes of sleep loss could make you more likely to gain weight.
Why Sleep Deprivation Causes Weight Gain
Losing out on sleep creates a vicious cycle in your body, making you more prone to various factors contributing to weight gain.
"The more sleep-deprived you are, the higher your levels of the stress hormone cortisol, which increases your appetite," says Breus. And it's not like you're going to be suddenly more ravenous for kale salads either. It takes willpower to choose the salad over the sandwich. When you're tired, you're more likely to go for the least effort as possible, easy and makes you feel good in the moment.
Often, that means reaching for bad-for-you foods. "When you're stressed, your body tries to produce serotonin to calm you down. The easiest way to do that is by eating high-fat, high-carb foods that produce a neurochemical reaction," Breus says.
A lack of sleep also hinders your body's ability to process the sweet stuff. "When you're sleep deprived, the mitochondria in your cells that digest fuel start to shut down. Sugar remains in your blood, and you end up with high blood sugar," says Breus. Losing out on sleep can make fat cells 30% less able to manage insulin.
When you're wiped out, your hormones go a little nuts, too, boosting levels of ghrelin, the hormone that signals hunger, and decreases leptin, the hormone responsible for satiety. In fact, sleep-deprived participants in one small study of 30 people ate an average of 300 more calories per day, according to research in The American Journal of Clinical Nutrition. And a larger study of 225 people found that those who only spent four hours in bed for five consecutive nights gained almost two pounds more than those who were in bed for about 10 hours, over the course of a week.
One reason you might be packing on pounds when you're sleep deprived is because your body goes into survival mode. Sleeplessness can fool your body into thinking you're in danger. "Your metabolism slows because your body is trying to maintain its resources, and it also wants more fuel," says Breus. "I would argue that sleep is probably the most important thing a person can do if they're ready to start a diet and lose weight," he adds.
How to End Your Cycle of Sleep Deprivation
Luckily, there are ways to make sure sleep never gets in between you and your goal weight again. First, figure out your bedtime. Count seven and a half hours before the time you need to wake up. That's your "lights out" time, which should ensure you're getting enough sleep to make your body wake itself up at the proper time (maybe even before an alarm goes off). And keep that wake-up time consistent, Kennedy recommends. "Doing that and getting out of bed at the same time sets your body's clock so you'll be tired around the same time every night", she says.
If you feel like you're still having sleep issues, keep a sleep diary that you can take in to a doctor. "Try to really get a sense of what's going on day-to-day. Record what time you're going to bed, roughly what time you fall asleep, if you're waking up in the middle of the night, when you wake up in the morning, and what time you get out of bed," says Kennedy. Also make sure to jot down other sleep-related markers, like how you feel in throughout the day, exercise, caffeine intake, alcohol and stress levels.
Most important of all, make sleep a priority. "It's physically unhealthy to lose sleep. And it's such an easy fix in theory," says Kennedy. "It requires both a behavioral and conceptual shift. Sleeping isn't downtime. You're feeding your body just as you are when you eat."