Tech + Health

01.17.16 5:15 AM ET

This Is Your Body on Sleep Deprivation

By Sara Gaynes Levy, Life by Daily Burn

Do you know when the last time you got a full night’s rest was? If you can’t remember, well, you’re not alone, but your body is definitely asking for some serious snooze time—whether you can feel it or not. The American Sleep Association recommends eight hours of sleep each night and, though it varies slightly from person to person, you may start feeling the effects as soon as you dip below 7½ hours a night, says James Maas, Ph.D., former professor and chair of psychology at Cornell University and author of Sleep for Success.

“If you’re not wide awake and alert all day long from the sleep you got last night,” says Dr. Maas, then you’re suffering from some degree of sleep deprivation. (So, yeah, basically everyone.) And trying to fix the problem by adding extra hours to your snooze schedule on weekends can actually do more harm than good by messing with your circadian rhythms. “Your body never knows when to shut down,” Maas explains.

As hard as it may be to prioritize sleep (work-life balance is tough enough!), just taking a look at the consequences when you don’t get enough sleep might convince you to log more hours in bed. Here’s how not sleeping affects your body, from head to toe.

5 Ways Sleep Deprivation Affects Your Mind and Body

1. Your brain: If you’re sleep deprived, your mind slows down. A lot. Be prepared that the quality of your work may slide without rest. “There’s a reduction in the ability to concentrate, to make critical decisions and process information,” says Maas. “Memory is also affected—sleepy people are often forgetful too,” says Dr. Neil Kline, a representative for the American Sleep Association. It also becomes more difficult to take in new information, speak or write well and to think creatively. “Basically, you don’t have your A-game with you,” says Maas.

2. Your mood: You probably know from experience that a lack of sleep causes mood instability. (Who hasn’t been the office grouch after tossing and turning?) Specifically, it causes irritability and a loss of enthusiasm, says Kline. Anxiety is also likely to be higher after periods of sleep loss, says Maas.

3. Your appetite: “When you’re sleep deprived, you overeat,” says Josiane Broussard, Ph.D., researcher and assistant professor at the University of Colorado at Boulder. After a poor night’s sleep, your levels of ghrelin, a hunger-promoting hormone, are altered, with its levels increasing after meals. In other words, even when you’ve already eaten, you’re still hungry). On top of that, you’re not making great food choices when you do eat. “You’re more likely to go for high-carbohydrate, sugary foods,” says Broussard, instead of cleaner choices, like produce.

4. Your workout: Good luck getting in a solid sweat session if you haven’t slept well. “Sleep deprivation impairs physical performance and response time, and the pain threshold is reduced,” says Kline. Your form can also suffer, since your motor skills will also be impaired. (And we know form is key in everything from yoga to spinning.) If you do work out the day after a bad night’s rest, try to do so after 4 p.m. — the morning hours are the peak time for these delayed reactions, explains Maas.

5. Your immune system: “Sleep loss is cumulative,” says Maas. That means over time, it can cause a decrease in your ability to fight off infection. “So you might not notice tomorrow, from a short sleep last night, but after a few days you’re going to start to notice—you’re going to get sick. And if you’re sleeping six hours or less a night the whole week, you are going to be just as horribly off as someone who has pulled an all-nighter,” he says. Plus, Broussard found that one night of no sleep was just as detrimental for insulin sensitivity, a key predictor of type-2 diabetes, as six months on a high-fat diet. “What we found which was so shocking was that the effects of one night [of no sleep] were pretty much the same [as the high-fat diet], the number one risk factor [that can cause type-2 diabetes],” Broussard says.

The Bottom Line

Your body needs sleep, period. “Time and time again, we’ve proven that people who think that six hours is all they need will get into car accidents, make stupid mistakes and are not able to exercise to the degree that they want. There are big consequences [when it comes to sleep loss],” says Maas. To stave off its temporary effects and find out how many hours you need to start feeling back to normal, Maas suggests adding 15 minutes of sleep per night back into your schedule until you can make it through a whole day without feeling your energy sag. However, keep in mind you may be so sleep-deprived you don’t know or remember what that feels like to be well-rested! “People tell me after they shift to even one more hour of sleep, ‘I never knew what it was like to be awake before.’”