To be a healthy, optimally functioning adult, you need between seven and nine hours of sleep every night. But how do you know if you’re good with seven and can afford to stay out for that extra drink, or if you actually need nine?
It’s a pretty essential thing to figure out, because sleep deprivation leads to a whole range of problems, from feeling like crap, to getting fat, to a higher risk of accidents. So we asked a sleep expert for some of the less-obvious signs that you’re not sleeping enough -- and if you feel tired, sleep!
You space out more than usual
A host of studies have shown that sleep deprivation is bad for cognition... otherwise known as thinking. If you realize that you were totally spacing out for the past 10 minutes, you just can’t seem to organize that simple memo, or you can’t remember what you did Thursday evening, then sure, you might have ADHD, you suck at your job, or you're drinking too much. Or it could be that you’re sleeping too little!
“Besides being sleepy or having to consume lots of coffee and energy drinks in order not to be sleepy, the other signs of too little sleep are shared with other kinds of problems,” says Harvard sleep expert Dr. Edward Pace-Schott. “But it’s pretty well known that the brain needs sleep in order to operate most effectively.” In fact, when someone is sleep deprived, there’s literally less brain activity going on up there. Attention, decision-making, and memory are among the functions that really start to slide when your sleep does.
You've turned into a jerk
You know when a baby starts crying and the weary, powerless (also sleep-deprived) parents begin to explain to all irritated onlookers that the baby either hasn’t eaten or hasn’t slept? Pretty much the same for adults! Just like being hangry, being sleep deprived can make you that person everyone tries to avoid as soon as they sense it’s one of those days. You know from experience to dodge the coworker going for an eighth cup of coffee, but researchers have specifically found that people who haven’t slept enough have “diminished emotional expressivity,” “impaired emotion recognition,” and “increased emotional reactivity.” Translation: your sleep-deprived buddy is insensitive to how you’re feeling, looks like everything might be fine, and then suddenly blows up at you. Just run.
You look like shit
You probably know the kind of morning when you glance in the bathroom mirror once and feel the need to avert your eyes. To determine just how noticeably shitty someone can look after not sleeping, researchers in Sweden took photos of 10 well-rested men and women, then had them sleep for only five hours the following day, pull an all-nighter the day after that, and pose for more glamour shots. When 40 study participants rated the photos on a bunch of facial characteristics, the results were pretty telling. After not sleeping, people had red, swollen eyes and dark under-eye circles. Ya don't say. Participants even observed that the sleepy people had more wrinkles and looked sadder. It’s not just you being hard on yourself: when you don’t sleep, you really do look terrible.
Sex doesn’t sound as good
Sure, when you’re really tired and need to catch up, you’re well aware that having some fun in bed is going to come at the cost of precious sleep time. In theory, it's always worth it. In practice, though, a guy’s testosterone and libido go way down without enough sleep. It also matters for the ladies: more sleep is associated with greater sexual desire the next day, and less sleep does just the opposite.
Your jeans don’t fit
If you’re sleeping five hours instead of eight, you’re also up for 19 hours instead of 16. That’s more than enough time to get hungry for an extra meal. And if you’re losing that sleep on the evening side of things, it's probable that those late-night eats aren’t the most wholesome part of your diet.
It gets worse. In people who got five hours of sleep as opposed to eight, levels of the hunger-suppressing hormone leptin were 15% lower, and levels of the hunger-inducing hormone ghrelin were 15% lower. Which doesn’t bode well for your clothes fitting.
You’re under the weather a lot
Illness always seems to hit you at the worst times, like when work is busy and you’re pressured to come in early and stay late. Or like when your social life is particularly, let's say, active, and you’re staying out late most nights of the week. You get sick, and you just can’t afford that shit right now.
It may be because you’re not sleeping as much as you should. Your immune system really relies on sleep. In fact, your body’s production of germ-fighting cells corresponds with your circadian rhythms. “You can look at certain kinds of immune markers in the blood -- inflammatory markers -- and they are increased by insufficient sleep,” explains Dr. Pace-Schott. “Too little sleep is a stress on your body, and it also lowers your immunity somewhat.” So make sure you prioritize sleep during those overly stressful (or overly fun) times.
It’s tricky that most of these could be symptoms of a bunch of things, but if you notice some of these symptoms after what you think was a good night of sleep, you do the math.
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