Sleep deprivation can wreak havoc on everything from mood to memory. Here's how to identify all the signs that you need more sleep.

By Real Simple Editors
Updated January 02, 2020
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In our always-on society, there’s great temptation, and even pressure, to shortchange sleep. In fact, there's a real misconception that sleep deprivation is some kind of heroic feat, a boastworthy indication of how hard you work, how early you can wake up, how little sleep you (think) you need, how active and social and busy you are.

But sleep isn't just a cozy reward after a long day—and it's certainly not a sign of laziness or weakness. Sufficient sleep—which for adults is defined as getting at least seven hours per night by the CDC—is an absolutely vital driver of every physiological system in the human body. When we’re sleep deprived—which more than one third of adults are—our health and wellbeing can suffer in myriad ways: mental, physical, and emotional.

You don't need to have pulled an all-nighter, or find yourself falling asleep mid-sentence, to be considered technically sleep deprived. In fact, you may not even realize you're not getting enough sleep, because you might not feel particularly tired. There are many less obvious signs of sleep deprivation that go beyond yawning, nodding off at your desk, or having heavy eyelids. But getting less than seven hours of sleep a night is all it takes, and the effects are subtle, but cumulative. In his book Why We Sleep: Unlocking the Power of Sleep and Dreams, professor and director of UC Berkeley’s Sleep and Neuroimaging Lab, Matthew Walker, PhD, describes scientific research that concludes: sleeping for only six hours a night for 10 days can make you as impaired as someone who’s been awake for 24 consecutive hours.

To avoid long-term health issues and improve your day-to-day life, here's how to identify seven sneaky signs of sleep deprivation.

1. You're exceptionally moody.

Sleep and emotional health are deeply interconnected. Patients with anxiety and depression are more likely to report chronic insomnia, according to statistics from the Harvard Medical School. And even short-term, partial sleep loss can negatively affect mood, outlook, and the quality of our most important relationships. “If you’re sleep deprived, you’re more vulnerable to crankiness, irritability, and challenges coping with stress,” says Lauren Hale, PhD, a professor in the program in public health at Stonybrook University and the former editor-in-chief of the Sleep Health journal. Sleep deprivation and stress can also create a nasty cycle: anxiety makes it harder to fall asleep, and then lack of sleep makes us more sensitive to the pressures of every day life, she explains.

2. Your productivity and performance are slipping.

Chronic sleep deprivation can negatively affect our abilities to reason, focus, and even find the right words to describe simple things, creating a cumulative, monumental effect in the workplace. In fact, insomnia alone is estimated to cost the American economy a staggering $63.2 billion annually in lost productivity, according to the Harvard Medical School. Often we believe it’s absolutely essential to stay up late finishing up work projects or preparing for presentations. But, it turns out, stopping work in time to wind down and get a good night’s sleep is generally the best way to improve productivity and performance overall.

In a wide range of sleep studies dating back almost 40 years, Robert Stickgold, PhD, director of the Center for Sleep and Cognition at Harvard Medical School, has discovered that nighttime sleep and dreaming promote new learning, memory consolidation, and greater creativity. Lately, however, Stickgold has also shown in newer experiments that daytime naps may do as much good for memory processing as a full night’s sleep. Naps even seem to trump coffee as a workday boost (although drinking a cup of coffee before taking a nap is known to be the ultimate pick-me-up combo). Caffeine does boost cognitive power for up to a half hour, “but sleep actually takes the recent information you’ve learned and files it away so you can more effectively take in new information,” Stickgold told Time magazine.

3. Your appetite is insatiable and/or you’re gaining weight.

Back in 2004, a large-scale, long-running Wisconsin Sleep Cohort study showed found that people who sleep fewer than six hours every night are more likely to be overweight. This group shows reduced levels of the appetite-suppressing hormone leptin, along with elevated levels of the hunger-stimulating hormone ghrelin. When we're overtired, we tend to reach for more snacks more often and give in to cravings for instant gratification, cravings we might otherwise be able to tamp down.

More recently, researchers have identified a strong connection between lack of sleep and increased risk for developing Type 2 diabetes, a metabolic disorder frequently triggered by overeating and obesity. This prompted the medical journal Lancet to argue that, given the “24/7 lifestyle of modern societies,” doctors everywhere should work harder to “motivate their patients to enjoy sufficient sleep” as a way to prevent—and treat—both obesity and diabetes.

4. Your skin is suffering.

Red, puffy eyes, dark undereye circles, and turned-down corners of the mouth were all readily identified in sleep-deprived people who participated in a Stockholm University study. “People can usually tell if you’ve had a rough night,” says Lauren Hale. “Even small amounts of sleep deprivation affect your appearance.” While a good concealer can help you feign a rested face, it's not a long-term solution for a fresh complexion and healthy skin. Sufficient, good-quality sleep should be a pillar of any skincare routine.

5. Your judgment is faltering.

Both accurately reading social situations and making good decisions depend heavily on the brain’s capacity to process emotions. But when people are sleep deprived, the region of the brain involved with emotional processing, the prefrontal cortex, “basically goes to sleep,” according to Harvard Medical School sleep researcher William Killgore, PhD. And there’s evidence being sleepy makes people sneaky, too: Sleep-deprived employees are more likely to cut corners and take credit for others work, according to research reviewed by organizational psychologists Thomas W. Britt and Steve M. Jex in their new book Thriving Under Stress. Why? “Presumably,” write Jex and Britt, not getting enough Z's results in “a reduced amount of self-control.”

6. Your libido’s flagging.

Fatigue can be an important factor when it comes to why women aren’t in the mood for sex. In particular, women involved with caring for children and aging parents frequently report being too exhausted for intimacy at the end of the day, according to the Mayo Clinic. And untreated sleep apnea—a sleep disorder that disrupts breathing and is estimated to afflict more than 18 million Americans—has also been linked to loss of libido in women. If you suspect your waning sex drive—or any other symptom of persistent fatigue—may be related to a serious health condition, such as sleep apnea or insomnia, it’s important to seek treatment for the underlying problem.

7. You're getting drowsy during the day.

This is one sign of sleep deprivation that might seem fairly obvious—but feeling exhausted during the daytime hours is a big red flag that you aren’t clocking enough sleep at night. And the symptoms can be subtler than yawning every five minutes or needing an IV drip of coffee to prop yourself upright (think: nodding off during a boring meeting). And daytime drowsiness is more than just a nuisance—it’s also a major public health problem. The CDC reports that more than 30 percent of Americans are chronically underslept, with potentially deadly consequences: Nodding off at the wheel is estimated to cause up to 6,000 traffic fatalities per year.

In case it hasn't been made clear, most adults need seven to nine hours of sleep, and increasingly, pre-bedtime use of tablets, phones, and other screens appears to be an important factor contributing to our collective slept debt, according to Hale. Late-evening use of screens not only suppresses the normal rise in melatonin, the hormone responsible for regulating sleep, but it revs us up when we should be winding down, says Hale: “Whether you’re watching TV or engaging in social media, the experience can be very psychologically stimulating, increasing alertness and making it harder to fall asleep. Powering down before bedtime is so important.” Try reading, journaling, stretching, or meditating to help your mind and body wind down before lights out.