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Though you’re unconscious for much of the night, what happens while you’re plastered to your mattress and snuggled up with your favorite pillow is deeply interconnected with your overall quality of life. Getting the right amount of sleep can completely change how you feel during the day.
There are the obvious signs of sleep deprivation. You just feel plain-old tired, or you know for a fact that you’re not meeting the generally recommended seven to nine hours of nightly rest. (Spoiler alert: More than a third of American adults don’t get enough sleep.) But what are some of the more discreet indications you need more zzz’s?
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You feel drowsy or have a slower reaction time
It’s normal to experience some sleepiness during the daytime—there’s a lull in your circadian rhythm in the afternoon. “There’s going to be a dip around 3 o’clock, regardless,” says Rebecca Spencer, a researcher at the University of Massachusetts Amherst who specializes in neuroscience and sleep.
But when you start feeling sleepy and it’s not in that typical siesta window, it could be a sign that you didn’t get enough sleep, she says.
“You should still be ‘on’ in the morning,” Spencer says. The same holds true in the evening before your usual bedtime, she adds. Really, if you're feeling tired any time that you typically don't, it's probably a red flag.
Not getting enough sleep can also result in grogginess or what Spencer calls “brain fog,” which is simply when you’re not thinking clearly. How that manifests can be different from person to person. You may feel as though a word is on the tip of your tongue, but you’re not quite able to grasp it, she says. You could also seem particularly forgetful—you look something up only to forget it within a few minutes. “It’s a general sense your brain is running at a slower pace,” she says.
Reaction time is also sensitive to poor sleep, according to Spencer. You may find yourself trying to grab the phone before the last ring and just missing it. These decision-making processes rely on two more intense cognitive functions. “It requires high level attention and requires cognitive control to know what is the task that I'm doing, and how to respond accurately and how to respond quickly,” she explains.
You more frequently give into cravings
Sometimes we all want that second or third piece of chocolate. But if you’re feeling extra inclined toward reaching for the bag of potato chips or Reese’s Cups, it might be because you’re tired.
“Just one night [of insufficient sleep] is enough to alter appetite and cravings,” nutritionist Dina Aronson says. “Sleep deprivation disrupts our normal, delicate balance of appetite-regulating hormones, which results in an increased desire for high-calorie, salty, sweet or fatty foods—even when we’re not hungry,” adds the director of nutrition programming at Diet ID, a a digital diet assessment and tracking platform. (Of course, there’s variation from person to person.)
Hormones leptin and ghrelin are the key players here—and they’re both tied to sleep. Leptin decreases your drive to eat following a meal. Ghrelin, in contrast, “increases appetite and is released when your blood sugar drops and your body needs food,” she says.
Studies have found that when you don’t get enough sleep, leptin levels in the bloodstream decrease, Aronson says. “The less leptin in your blood, the weaker your signal is to stop eating—which translates into increased hunger.” What’s more, a lack of sleep is also associated with higher levels of ghrelin, meaning you may feel hungrier when you’re sleep-deprived than in days following a perfect night’s rest, she says.
Cravings are a complex biological process. They can be triggered by any number of things, even the smell of fresh cookies at the supermarket or a commercial for ice cream, Aronson explains. When your brain registers the stimulus, it releases dopamine, a hormone that’s associated with the pleasure and desire to eat a given food, she says. Your salivary glands may be activated in preparation for chewing and digesting a food. Then you get the final message: Your brain tells you to eat the cookie, which will fuel the dopamine response and elicit pleasure.
It’s true that we have cravings on a regular basis. What's different is that when you haven’t slept, your inhibitory control is weaker. Higher-level cognitive functions are what help your rational self resist the temptation to do something that you know you maybe shouldn’t, like eating a cookie.
Aronson isn’t aware of research showing you’ll crave different foods when short on sleep, but she says the cravings you typically have may be amplified. "Improving sleep habits is a powerful strategy to reduce the frequency and intensity of cravings," she says.
Your skin looks worse for wear
We’re all familiar with the dark circles and under-eye puffiness that emerge when we don’t sleep enough. An increase in blood flow causes the vessels around your eyes to dilate and become more prominent. Bags under the eyes are the consequence of blood vessels becoming leaky, says Dr. Ivan Vrcek, a medical doctor who specializes in oculoplastic surgery, or procedures related to the eyes. This may be due to the body’s limited time to restore and repair itself after sleep.
There are other changes that happen in the skin after a bad night’s sleep. Dr. Elma Baron, the chief of dermatology at Northeast Ohio Veterans Affairs Medical Center and professor at Case Western University, was one of the authors of a paper that demonstrates a connection between poor sleep and skin aging. Sleep-deprived women had indicators of premature aging, such as fine lines and uneven pigmentation.
There were also findings that your nighttime habits affect your ability to heal from sunburns. "[Those with better sleep] were able to recover sooner from the sunburn... than those who had poor sleep,” Baron says. Another team of researchers had related findings when looking at shift workers. Its research found that circadian disruptions were tied to a potential increase in the risk of developing melanomas.
Pesky pimples may also be connected to sleep. “Those with acne also report they don’t sleep well,” Baron says. Whether there’s a direct relationship isn’t as clear. There are other factors such as stress that could play a role, according to Baron.
But acne is considered an inflammatory disease, and other researchers have found that a lack of sleep, even for one night, has been shown to increase inflammation. (The uptick was only present in female subjects, the authors note.) Other experts have even suggested managing sleep patterns as one way to potentially improve adult acne.
What to do if you realize you need to get better sleep
The best solution to sleep deprivation is, quite simply, to sleep. Try taking a nap during the day after you missed out on a couple hours of rest. Though Spencer cautions not to oversleep and mess up your ability to doze off that evening.
Alternatively, you could try to supplement the following night’s sleep, but she adds: "It's pretty hard to do.” For instance, “if I lost four hours last night and I’m normally an eight-hour sleeper, [I’d need] my body to sleep 12 hours straight.” Spencer explains that there are two reasons that it’s challenging for your body to add four extra hours: First, from a metabolic standpoint, people need to eat every so often. Second, your circadian rhythm isn’t really designed to let you sleep that long.
In other words, it’s really important to try to stick to the seven-to-nine hour window as much as possible. Here are a few tips to set you up for success:
Make sure your bedroom is a sleep-friendly environment. Drop the temperature a few hours before you go to bed, ideally to the mid 60s to low 70s. This range will help match the natural circadian rhythm, and may improve your sleep. If the last thing you’re trying to do is add another item to your daily to-do list, a smart thermostat can be an easy answer. A set of blackout curtains could also come in handy—though it is useful to have some light exposure in the morning.
Put your electronics away before bedtime. It’s tough to step away from our ever-connected world, but your sleep will thank you. Screens interfere with melatonin production, even if you’re using a sleep-friendly phone setting that purports to decrease blue light.
Consider using a sleep tracker if you want more information. These devices aren’t universally beneficial, but a sleep tracker can be a great tool for identifying patterns of sleep distruption. Your fitness tracker may already have these capabilities, and there are bedside devices such as the Google Nest Hub that you don’t need to worry about recharging. Its Sleep Sensing is the most accurate we’ve come across so far.
Be mindful of your nighttime diet. Eating heavy or sugar-laden food can disrupt sleep. Additionally, be weary of consuming alcohol and caffeine in the late afternoon.
Don’t stress too much about your sleep. Getting enough rest is essential to your health and well-being—but it’s counterproductive to worry about it all the time. One poor night of sleep will result in daytime effects, but it’s not the end of the world. If you’re feeling particularly stressed, or are a generally anxious person, a weighted blanket may provide some relief—though research on the blanket’s efficacy, for the general public and specific mental health conditions, is limited.
Maintain a sleep schedule and nightly routine. Going to bed and waking up around the same times every day will help you make the most of your body’s circadian rhythm.
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This article originally appeared on Reviewed: Sleep deprivation is fairly common—here are subtle signs to watch for