Lack of Sleep Makes You Fat and Unhealthy in So Many Ways

Woman asleep on the table
Cole Saladino/Thrillist

Think of sleep as your body's required daily tune-up. Just like some cars need more maintenance than others, some people need more sleep than others. But whether you need a seven-hour or nine-hour nightly reboot, if you don't get the sleep you need, your body will turn on you and make your life a living hell.

If you're sitting there saying, "Nah. I'm the exception. I can handle sleep deprivation just fine," well, enjoy your sleep-deprived delusions while you can, because it won't be long before they catch up to you, in all the following forms.

You'll start stuffing yourself silly

Even if you're not conscious of the tendency, you probably start grabbing greasy, sugary food -- and a lot of it -- when you're short on sleep. In fact, the American Heart Association quantified this chow-down to the tune of an extra 549 calories a day in a group of individuals sleeping roughly an hour and 20 minutes less than the group that maintained a normal level of sleep.

The kicker is that even if you're aware that sleep could screw with your eating habits, you may not be able to outsmart your hormones, which are basically responsible for the food fest. Dr. Caroline Apovian, the director of the Nutrition and Weight Management Center at the Boston Medical Center, explains, "When we do not receive sufficient sleep, our ghrelin (hunger) levels are up all day, and our leptin (satiety) levels are low. In addition, sleep interferes with our impulse control. Despite our best efforts to follow a healthy eating plan, the combination of high ghrelin and low impulse control will lead to overeating. Your cortisol (stress) levels will be high the day following a sleepless night as well, which also prompts overeating, especially on sugary and fatty foods."

So yeah, if you let this go on long enough, all those days, weeks, months, and years of extra calorie, fat, and sugar intake don't add up to a happy, healthy body.

You'll suck at exercise

If you think you'll just burn off all those extra calories you're eating with a little extra exercise, think again. When you're sleep deprived, you're, well, tired. And while research indicates that being tired doesn't actually compromise your gross motor skills or maximal exercise performance (for instance, lack of sleep can't actually make you any less strong), it does reduce your ability to exercise as long and it screws with sports-specific performance on skills like reaction time and hand-eye coordination.

Not to mention, the exercise you do while sleep deprived actually feels harder, even if it's your normal routine. The reasons for these responses still aren't entirely clear, but a review in the journal Sports Medicine points to a multi-pronged body revolt that includes a nervous system imbalance that simulates overtraining syndrome, increased inflammatory cytokines that screw with the immune system, and cognitive deficits that reduce your brain's ability to stay sharp and alert.

Your body will hurt to its deep inner core

You know inflammation is unpleasant -- it doesn't feel good when you get something stuck between your teeth and your gums flare up. It feels even less good when you throw out your back and you're laid up for days.

But know what feels even less, less good?

Chronic inflammation that takes place inside your body, where you can't see or feel it, but where it lurks, eroding away your good health, increasing your risk for major illnesses, including diabetes, arthritis, and heart disease. And it's not just chronic sleep deprivation that does the dirty. A 2008 study found that even a single night of sleep deprivation turns on the chemical pathways that trigger your immune system to turn against you.

Oh yeah, lack of sleep also reduces pain tolerance. So when your coordination is compromised and you trip over your own feet and stub your toe on the door frame, it's going to hurt a lot worse. (This highly specific example was totally not about me.)

It makes you dumberer

Or at least, not as smart.

Even if you've heard about how lack of sleep interferes with memory and brain function before, if you're low on sleep, you might need the reminder. Because, you know, lack of sleep and memory problems.

Dr. Vincent Passarelli, a clinical psychologist who works with clients regarding sleep disruptions, explains the phenomena, saying, "Research has shown sleep's 'reset' for our brain is necessary to prune neural circuits. Synaptic pruning is similar to gardening for the brain. It enhances neural connections by clearing away less-needed circuits and making room for more efficient ones to grow. Research has shown it to be related to increasing brain connectivity, retention of new information and memories, as well as eliminating certain proteins and plaques shown to be correlated with Alzheimer's and dementia."

In other words, if your brain garden hasn't been pruned in a while, all those extra weeds may be choking out your ability to string together coherent sentences or remember where you put your keys.

Plus, it can kill you

Like, for real. Aside from the fact that you literally can't live if you go long enough without sleep, driving while tired can be every bit as dangerous as driving while intoxicated. According to the National Highway Traffic Safety Administration, there were an average of 83,000 "drowsy driving" car crashes recorded each year between 2005 and 2009, with 37,000 of them resulting in injuries (which probably feel especially painful, BTW). And in 2014, 846 fatalities were attributable to drowsy driving.

If that's not enough to help you get some shut-eye, just remember it's not only your life on the line -- falling asleep at the wheel could kill someone else and ruin lots of lives forever.

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Laura Williams is a fitness writer and exercise physiologist who sucks at sleep. But really wants to get better. Follow her on Twitter @girlsgonesporty.