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The amount and quality of sleep you get any given night really sets the tone of the following day. When we’re well-rested, our minds and bodies just seem to work better. When we’re really tired, everything’s harder. We get cranky, can’t focus, and sometimes get sick. Skimping on sleep long term can interfere with pretty much every aspect of your health—from your skin to your immune system, to your ability to maintain a healthy weight.
In fact, skipping out on sleep can lead to weight gain for a few different reasons. Getting adequate zzz’s—both in terms of quantity and quality—is essential for regulating so many of our hormones, hunger cues, and physical abilities. Here’s how both your eating and activity habits suffer when you don’t sleep.
Being tired throws off hormones that control appetite, leaving you hungry all the time.
“A sleepy brain is the brain that craves,” Param Dedhia, M.D., director of sleep medicine and physician in the weight loss program at Canyon Ranch in Tucson, tells SELF. A lot of hormones and brain chemicals are responsible for regulating hunger cues, but the main players are leptin and grehlin. Leptin decreases your appetite, and grehlin increases it. When you don’t get enough sleep, leptin levels drop and grehlin levels rise, leaving you with a bigger appetite that can’t be tamed.
Not only does your tired brain crave food, but it craves sugary, salty, fatty foods specifically.
The reason isn’t so clear, but Joseph Ojile, M.D., medical director of the Clayton Sleep Institute, suggests it may be that our tired brains are just telling us to eat whatever will provide a quick hit of energy. “You want those calories to drive you to stay awake. Sugar and carbs make you stay awake at least in the short term,” he tells SELF. One recent small study published in the journal Sleep found that sleep deprivation impacts the cannabinoid receptors in the brain—the same ones that marijuana affects—giving us, essentially, the munchies.
“These foods have a high caloric density,” Ojile notes, meaning they pack a lot of calories per bite, “which is almost a surefire way to gain weight.” In fact, the Sleep study showed that subjects who didn’t get enough sleep were taking in about 300 extra calories per day, Ojile says. “That can cause weight gain of about 1 pound per week, or more.”
Sleep deprivation can also slow down your metabolism.
Not only are you eating larger quantities of unhealthier foods, your body’s also going to process them more slowly. Research shows that just a week of sleep deprivation can mess with metabolism, specifically interfering with the body’s ability to process glucose and leading to insulin resistance. Insulin resistance causes your body to store more sugar instead of breaking it down and using it for energy efficiently. Studies even suggest that being sleep deprived and experiencing this insulin resistance long-term can increase the risk of developing type 2 diabetes.
When you’re exhausted, it’s hard to find the energy to work out.
Getting sufficient sleep is an important part of staying active and fit. “We’re seeing more professional athletes talk about incorporating sleep as part of their overall fitness program,” Ojile notes. That’s because we need sleep to stay active. “It lets our brains and muscles rest and regenerate. It allows us to be more efficient hormonally. It allows our immune systems to work better,” Ojile says.
When we don’t give our bodies enough sleep, our movement patterns change, Dedhia notes. “If your body can’t repair, do you want to workout again the next day? Not so much,” he says. “You’re going to wait until the next day or some other time” when your mind and body feel more energized. If you continue to get too little sleep, you’re not going to hit the gym quite as often. When your activity level drops, you burn fewer calories and put on weight easier.
Getting more sleep can help reverse these effects, but that takes commitment.
If you’re struggling with weight gain and are always running on fumes, logging more shut-eye is a good, healthy first step to take. We all know how hard it is to get a good night’s sleep, but there are a few things you can start doing tonight to make a solid night of quality sleep more likely. Dedhia suggests creating a routine around bedtime that you look forward to each night. “Find a ritual, make it about you,” he says. Whether that’s reading a book, taking a warm bath, or lighting candles and listening to soothing music, set aside time for you to relax and wind down before bed. This will help calm your mind so you can ease into sleep faster. You should also clean up your sleep hygiene by doing things like ditching electronics before bed, putting down the coffee after 2 P.M. (at the latest), and simply putting sleep higher up on your list of priorities.
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