Sleep, Mental Health, and You: What You Need To Know

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Key Points

  • There's a deep connection between sleep, mental health, and general well-being.

  • Good sleep improves mood, memory, focus, learning, problem-solving, and decision-making.

  • Poor sleep leads to emotional instability, poor decision-making, impaired memory, stress, and a short attention span.

  • Mental illnesses associated with poor sleep include depression, anxiety, ADHD, seasonal affective disorder, bipolar disorder, and psychosis.

The connection between sleep, mental health, and overall well-being isn't always obvious. After all, many people have fond memories of their college years, when they partied a lot and slept little. Nonetheless, there's a great deal of evidence that sleep is good for your mental health — and lack of sleep causes problems.

The relationship between sleep and mental health is complex, and scientists are still learning about exactly how it works. Read on to learn more about what sleep does to support the brain, how too little sleep affects your mind, and the potentially vicious cycle of mental disorders and sleep disorders.

How Does Sleep Improve Mental Health?

In the classic children's book Peter Pan, J.M. Barrie created a memorable image of what happens to a child's mind when they're asleep. "It is the nightly custom of every good mother after her children are asleep to rummage in their minds and put things straight for next morning, repacking into their proper places the many articles that have wandered during the day … It is quite like tidying up drawers."

That's a fantasy, of course, but the "tidying up" really happens, in a way. it's just something your brain does to itself rather than relying on your mom. Six or eight times a night, you cycle through four stages of sleep, each involving a different sort of brain activity. As you go through them, you process your experiences during the day and consolidate your memories.

"Although there is still uncertainty about the function of sleep, it seems likely to involve restoration of the function of synapses," said Guy Goodwin, emeritus professor of psychiatry at Oxford University. "We all have the experience of sleep resting our mood after a difficult day. In positive mental health, we assume this mechanism is working well to provide resilience, even after bad days."

Studies show that good sleep improves people's mood, focus, and ability to learn and solve problems. Interestingly, there's also evidence that getting a lot of REM sleep — the stage that involves vivid dreams — improves creativity. There's value to those crazy dreams, after all!

The strongest evidence of how sleep supports mental health, however, is what happens to mental health when you get too little of it.

Woman awakes and stretches on edge of bed

The Effects of Lack of Sleep on Mental Health

Even if you have a basically healthy brain, poor sleep deteriorates its functioning and generally makes your day worse. Sleep deprivation impairs multiple mental processes, leading to changes in how you think and feel — mostly for the worse.

Emotional Instability

When you've slept badly, you often find that your emotions seem out of control — you snap at your spouse or suddenly break down crying without even knowing what's happening.

The likely culprit is the amygdala, sometimes colloquially called the "lizard brain" because it's the source of primal emotions like fear and rage. Research through MRI scans indicates that the sleep-deprived have more reactive amygdalas than those who've gotten a good night's sleep, which explains why sleeplessness makes you so moody.

Woman sits back in a chair and relaxes

Poor Decision-Making

Another part of the brain that sleep deprivation hinders is the prefrontal cortex. This portion is very busy during REM sleep. However, during waking hours, it helps regulate the brain's executive functions, such as planning, decision-making, and mediating emotions from the amygdala. If you know Freudian terms, it's like the ego to the amygdala's id.

Sleep deprivation impairs the connections between the prefrontal cortex and the rest of the brain, so it may no longer perform its executive functions as well. Not only does this leave you at the mercy of your amygdala, it often leads to bad decisions. Did you wonder what the heck you were thinking when you bought that feathered pink hat? Maybe you needed more sleep.

Impaired Memory

Another function that the prefrontal cortex regulates is working memory. As noted earlier, sleeping well helps you learn and remember things, so conversely, a lack of sleep makes it easy to forget things and difficult to retain new pieces of information. Thus, pulling all-nighters before exams is not a great idea; just do what your mother says and pay attention in class.

Couple sleeps soundly on a bed


Lack of sleep also mucks around with your hormones. Most people associate hormones with sex, but they're players in all emotional states. One of the better-known of these non-sexual hormones is cortisol, sometimes called "the stress hormone."

That name isn't entirely fair because, most of the time, cortisol just keeps you alert and awake. It's only when you sense a threat that it amps up into that "fight-or-flight" response. During the course of a normal day, your cortisol declines in the evening while melatonin (the sleep hormone) rises; then, as morning nears, the melatonin declines and cortisol rises, and you wake up.

When you don't sleep or sleep lightly, your cortisol level remains high all day and night. This, combined with the touchy amygdala, makes you much more stress-sensitive.

Short Attention Span

All these factors combined — the overactive amygdala, the underactive prefrontal cortex, and the surplus cortisol — create a lot of cross-currents in your brain, so it's no wonder that it makes it difficult to stay focused. With too little sleep, you likely find your mind wandering off when you need to concentrate, making it difficult to complete tasks.

This also makes driving more dangerous; while the price of "drowsy driving" is difficult to estimate because there's no way to test for drowsiness, experts believe it accounts for a significant percentage of traffic deaths.

Sleep and Mental Disorders

Those qualities make life more difficult for you and anyone around you, but they aren't in themselves mental illnesses. What about more serious problems?

The effects of poor sleep on mental health are a little tricky to tease out because sleeplessness is a common symptom of many mental ailments. However, there is evidence that the causation works both ways, and lack of sleep worsens or even initiates common mental problems. Here's a quick rundown of some common mental health issues and how they relate to sleep.

Man sleeps on a pillow with an eye mask


When it comes to sleep, depression cuts both ways: sometimes, it leads to too little sleep (insomnia), sometimes to a lot (hypersomnia). However, Insomnia is a much more common issue, especially among older persons.

It's not hard to see why depression could trouble a person's sleep; even people who aren't clinically depressed know what it feels like to lie awake when grieving a lost loved one or a broken relationship. However, at least one sleep disorder might be responsible for bringing on depression in some people.

A large CDC study of people with sleep apnea — impaired breathing during sleep — found that depression was twice as likely to develop in men and five times as likely in women as it is in people without sleep apnea. Researchers theorized that lack of oxygen to the brain disrupted its normal functioning, increasing the risk of mental problems.


Anxiety bears the most obvious relationship to lack of sleep: to fall asleep, you need to relax, and anxiety is the opposite of relaxation. The aforementioned cycle of cortisol and melatonin is the main reason for this, though other hormones and brain functions are involved. Anxiety disorders keep people tense and on edge, disrupting that cycle.

Too often, this difficulty sleeping itself becomes a source of anxiety. As Snooze noted, the Sandman has an annoying habit of staying away the more you want him to show up. This leads to a vicious cycle where the lack of emotional control from sleep loss makes it more difficult to control anxiety, but the anxiety further deprives you of sleep.

A related issue is that some of the most popular drugs that treat depression and anxiety have insomnia as a possible side effect. This is why many users like to take them in the morning.

Woman looks at phone late at night

Attention-Deficit Hyperactivity Disorder (ADHD)

ADHD also has a strong correlation with sleep problems. Younger people who have it often have trouble falling asleep and staying asleep, while older adults with the condition are more likely to develop sleep apnea and restless legs syndrome (twitchiness in the legs that impairs sleep). The fact that the drug most often used to treat it is a stimulant doesn't help matters.

Relatedly, one large study found that sleep-disordered breathing (which includes both snoring and sleep apnea) among young children was a substantial predictor of behavioral problems in general. This isn't surprising when you consider the ways listed earlier that sleeplessness might make normal people more impulsive and erratic; imagine the effect of it happening night after night.

Seasonal Affective Disorder

Seasonal affective disorder is a type of depression related directly to sleep disruption. In regions with pronounced variations in day length, some people feel depressed during the seasons with shorter days and longer nights.

This condition demonstrates the importance of the circadian rhythm, which governs the body's internal cycle of sleeping and waking. Other disruptions, like jet lag and working the night shift, similarly increase the risk of bad moods and mental impairment.

Bipolar Disorder

People with bipolar disorder swing between manic and depressive phases, with differing effects on sleep. During the depressive phase, sleep is much like that of other people with depression. During the manic phase, people are full of energy and don't sleep much, but it doesn't bother them because they don't feel that they need much sleep.

However they feel about it, the lack of sleep still isn't good for them. In fact, there's evidence that even when people manage the disease, sleep deprivation may trigger a manic relapse. Keeping a regular sleep schedule may help keep bipolar symptoms under control.


Sleep deprivation is a common technique involved in torture and brainwashing, not just because it's miserable but because it makes the victim's mind lose touch with reality. Studies have found that when people go 48 hours or more without sleep, they start getting hallucinations, delusions, dissociation, loss of a sense of time, and generally altered perceptions. In other words, just a few days without sleep might cause a total mental breakdown.

Fortunately, sleep deprivation psychosis (as it's called) passes once you get proper sleep again, though, of course, if you've been tortured or brainwashed, you'll likely have longer-term consequences.

However, people with longer-term psychotic disorders like schizophrenia often find their symptoms worsen with poor sleep, and poor sleep often co-occurs with psychotic disorders.

Woman cuddles up with blanket and pillow sleeping

Managing Sleep and Mental Health

As all of the above demonstrates, sleep disorders and other kinds of mental health issues often go together. Since there's such a diverse range of illnesses here, there's no one way to handle them all. If you have both a mental health issue and trouble sleeping, you need to consult with your healthcare provider to develop a personalized plan to address all your concerns.

The main takeaway here is that even if you don't currently have a mental problem, sleeping too little or too erratically stands a good chance of making you develop one. The temptations of skipping a little sleep are all around us — work, parties, sex, video games, the next episode — but try to keep a stable sleep schedule as much as possible. Your future self will thank you for keeping you sane.

Learn more about the connection between sleep and mental well-being on Snooze.

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