5 Ways Sleep Deprivation Affects Your Brain and Mood, According to Sleep Doctors

Your mind needs sleep just as much as your body does.


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Parents of newborns, students cramming for exams, overworked professionals pushed to their max, insomniacs, caffeine dependents, night-shift workers, and menstruating people—at some point, we all know how getting less than enough sleep feels (very bad). Though it’s normal to have trouble falling asleep and/or staying asleep occasionally, prolonged periods of sleepless nights and chronic sleep deprivation can harm not only our bodies, but our minds.

Sleep is essential for brain development, wellness, and functioning, explains Heidi Riney, MD, board-certified sleep medicine and neurology psychologist and the chief medical officer of Nox Health. “Sleep has long been thought to be a passive process, but it’s actually an active state, and the quality and duration of our sleep impacts crucial brain functions,” she says, including memory storage, attention maintenance and arousal, learning new material/tasks, mood stability, the ability to read social cues, problem-solving, executive functioning, and impulse control.

So what happens to your brain health and mental capacities if you consistently don’t get enough sleep? And how can you power through on days when you didn’t get enough shut-eye the night before? We asked sleep specialists and mental health experts to weigh in.

How Much Sleep Do You Need for Optimal Brain Health? 

Though it seems like a straightforward question, it’s somewhat complicated to understand how much sleep your mind needs to perform well and stay well. The human brain is as different from one person to the next as fingerprints. Because of this, the specific amount of optimal sleep one brain needs isn’t the same for everyone, says licensed clinical psychologist Bethany Cook, PsyD.

Generally speaking, Cook says, scientists have found that most adults need around 8 or 9 hours of sleep to perform and feel their best. However, since this estimate is a bell curve, some people need more, and some need less to feel great. 

Though without undergoing formal sleep analysis, it’s difficult to know exactly how much sleep you need, there are a few things that can help guide your body’s natural cues. Quality and quantity of hours sleep do matter, but so does how you feel in the morning.

“The only way of knowing if you’re getting ‘quality sleep’ is if you typically wake up feeling rested, refreshed, and revitalized,” Cook says. “Our brains need around four to six full sleep cycles a night to wake [feeling] rested. If you're sleeping for 10 hours every night, but not waking up feeling refreshed, you’re getting poor sleep quality.” She adds that it can be helpful to visit a clinic for a sleep study to identify and fix the problems in your sleep cycle.

The Mental Health Effects of Sleep Deprivation

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A Slower Response Time

Even if you didn’t have a single sip of wine last night, you might wake up feeling foggy and sluggish, unable to respond to questions or respond to things happening around you quickly, explains Nicole Avena, PhD, research neuroscientist, psychologist, and a wellness ambassador for Nature Made. 

“Lack of sleep, short term, has been linked to poor response times and processing,” she says. “This not only can impair your awareness, but it can also harm others around you. Demanding cognitive functions, for example, driving, cannot be performed adequately when sleep is hindered.”

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Short-Term Memory Disruption

When you miss your date with Mr. Sandman, the next day may likely bring a struggle to remember much of anything: your keys, your wallet, your phone, you name it. According to Taz Bhatia, MD, board-certified integrative medicine physician and OLLY ambassador, this is because there is a connection between sleep and its impact on memory retention. “Sleep is essential in consolidating memories and allowing us to retain and recall information,” she says. “However, this process can be disrupted without enough sleep, leading to difficulties forming, keeping, and calling back memories.”

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Increased Appetite and Cravings

After tossing and turning for hours, you finally leave your bed and head straight to the kitchen. What do you reach for? Probably simple carbohydrates and sugar, since one common effect of sleep deprivation is increased hunger by 24 percent, says Melissa Halas, MA, RDN, CDE, registered dietitian and brain health expert for Neauriva. 

“Often, the carbohydrates consumed aren’t nutrient-dense foods like apples, or whole grains, but rather simple carbs like snack foods high in refined sugars or refined grains,” she says. So if you’re wondering why you can’t stop craving sugar, maybe you should take a look at your sleep patterns first.

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Trouble Making Decisions (Large or Small)

Depending on what type of career path you’re on, the ability to make fast decisions is vital to your success. Think: operating heavy machinery, responding to an emergency, or managing a large team with many moving parts. (And let’s not even get started on all the decision-making that also needs to happen at home.) Even if you don’t have a high-stakes job, being able to make simple decisions, like what to wear for the day, is impacted by sleep. Avena explains that our brains process things differently when we don’t get enough sleep. “What’s called ‘naturalistic decision making,’ or being able to make everyday decisions, like what to have for lunch, can be altered,” she says. “This is due to the prefrontal cortex lacking adequate rest.”

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Difficulty Regulating Emotions

Maybe you don’t usually have a short fuse with your partner and friends, but every interaction might feel tense and irritating when you’re running on only two hours of rest. This is because people who don’t sleep well or enough often feel snappy, depressed, and more likely to make risky choices, according to Avena. “There’s no need to break up with your boyfriend after days of not sleeping properly, but your brain may think otherwise,” she says. “Sleep plays a role in the brain to regulate and process emotions, which affects how we react and manage emotions every day.” If you’re mood seems like it’s on a chaotic roller coaster, part of the reason may be that you (and your brain) are under-slept, leading to quick tears, more flashes of frustration, negative reactions, and the like.

How to Cope if You're Running on Little Sleep

We all have our reasons for sleepless nights once in a while, and in these cases, while making sure to catch up on sleep A.S.A.P. is the best solution, it's not always an immediate possibility. Here are some of the healthiest and most effective ways to power through and compensate for any mental glitches that come with occasional sleep deprivation. But don't rely on these tips as an excuse to skimp on sleep! They're temporary bandages, not the final fix for sleepiness.

Get outside.

You might want to crawl under the covers and hide from the world after a restless night, but you should do the opposite, as sunlight and fresh air are both great for triggering endorphins and serotonin, Avena says. “Serotonin, in particular, is a melatonin precursor and can help fight insomnia together,” she says. “It can be as easy as sitting on your porch for your morning coffee.”

Listen to music to wake up your brain.

Taylor Swift can get you through a breakup, and she might also help your brain power through a tough day. When you need an energy boost on sleepy mornings, turn up the volume on your favorite, upbeat playlist while driving or taking a shower. Believe it or not, when you listen to music, your entire brain lights up with neuronal activity, getting the entire brain ‘online.' Cook says: “While all the parts are awake and working, music’s vibrational energy will inevitably sync your own body's internal energy to match the faster, higher and happy vibrations.”

Caffeinate (responsibly).

Although turning to too much caffeine habitually to make up for poor sleep isn’t wise, there’s little downside to using it as a wakefulness tool every now and then, says Valerie Ulene, MD, MPH, cofounder of Boom Home Medical. “A caffeinated beverage early in the day will almost certainly help keep you more alert for a few hours,” she says. “Just remember to avoid caffeine after about mid-day as consuming it too close to bedtime will likely cause more problems than it solves.”

Try to find the root issue.

Though you may need to power through the day after a poor night of sleep, it's crucial to try to identify the reason you’re not sleeping the night before and address it before it becomes a chronic issue. 

“It can take days to catch up from even losing one hour of sleep the night before, so it’s best to try and maintain a consistent sleep and wake schedule and allow yourself to get at least seven hours of sleep each night,” Dr. Riney says. “If you feel you’re experiencing poor quality sleep or have daytime dysfunction that may be attributed to poor sleep, it’s important to seek out a sleep specialist for further evaluation.”

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