Having trouble thinking creatively? Not able to focus on tasks that need to get done? Poor sleep could potentially be to blame. It turns out sleep deprivation can do a number on your brain—and not just in the short term.
Here’s what you need to know about sleep and the brain, from the proven ways sleep enhances brain function to what’s really going on in your noggin while you snooze.
Why sleep is important to the brain
Sleep is crucial for keeping your brain healthy. Below are five research-backed brain benefits of sleep.
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Thinking in new, imaginative ways requires a well-rested brain. Conversely, a sleep-deprived brain is unable to think creatively.
A study reported in the journal Nature bears this out. For the study, participants learned a task in which they had to recognize a hidden pattern in the questions they were asked. Their initial training was followed by eight hours of nighttime sleep or wakefulness or daytime wakefulness.
More than twice as many participants gained insight into the hidden rule after sleep as those who did after wakefulness, regardless of the time of day. The researchers concluded that “sleep, by restructuring new memory representations, facilitates extraction of explicit knowledge and insightful behavior.”
For example, your brain doesn’t need to retain every sensory impression accumulated during your waking hours. You might say that sleep helps the brain separate the wheat from the chaff of your everyday life.
Protects against dementia
People who have certain sleep disorders, like insomnia and sleep apnea, are more likely to develop dementia symptoms. This makes sense, given that the brain’s ability to clear out the toxic waste buildup only operates during sleep.
It’s important to note researchers can’t say for certain poor sleep causes Alzheimer’s disease or dementia. But what they do know is getting quality sleep each night is essential for removing harmful beta-amyloid and tau proteins from the brain.
Improves cognitive function
Anyone who’s ever stayed up all night knows even one night without sleep affects your ability to think clearly, focus your attention, or make decisions. Studies show sleep deprivation can impair your mental function as much as being intoxicated.
On the flip side, getting quality sleep goes a long way toward boosting your brain. For a study published in the journal Sleep, researchers looked at the effects of sleep on cognitive function. They noted the optimal amount of sleep for cognitive function is seven to eight hours. They also suggested even one night of good sleep could improve it.
Depression is often influenced by chemical imbalances in the brain, and depression and sleep problems go hand-in-hand. People with depression may either have a hard time sleeping or else get too much sleep.
While it’s not clear if sleep deprivation causes depression, it can worsen it. Studies show people who sleep fewer than six or more than nine hours a night are more likely to be depressed than those in between.
Those who have insomnia also are much more likely to have depression and anxiety than those who sleep well. This may be due to the disruption of the body’s circadian rhythm, the daily sleep-wake cycle, in people with depression.
Making lifestyle changes like limiting food, caffeine, and alcohol too close to bedtime, practicing meditation, and trying cognitive behavioral therapy can make it easier to get a good night’s sleep and, in turn, reduce depression symptoms.
What happens to your brain during sleep
There are two main types of sleep: rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. There are five stages of sleep total, made up of four NREM sleep stages and one REM sleep stage, all of which you cycle through multiple times during the night. Each stage is linked to specific brain waves and activity.
Here’s what happens to your brain during each stage of sleep.
Stage 1: During this short, several-minute period of light NREM sleep, your heartbeat, breathing, and eye movements slow. Your muscles relax and may twitch, and your brain waves start to slow down from their daytime wakefulness patterns.
Stage 2: In this light NREM sleep period, your heartbeat and breathing slow down and your muscles relax even more. Your body temperature drops and your eye movements stop. Brain wave activity is slow, but there are brief bursts of electrical activity. Stage 2 sleep accounts for the biggest share of your repeated sleep cycles.
Stages 3 and 4: These so-called deep sleep stages, also part of NREM sleep, are what allow you to feel refreshed in the morning. Deep sleep lasts longer during the first half of the night. In these stages, your heartbeat and breathing slow to their lowest levels. Your muscles are relaxed and you may be hard to wake up. Brain waves in this stage are even slower.
REM sleep: During this lively period, first occurring about 90 minutes after you fall asleep, your eyes move rapidly from side to side behind closed eyelids. Brain wave activity is closer to what it is during wakefulness. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels.
Most dreaming occurs during REM sleep, though you can also dream during NREM sleep. Your arm and leg muscles become temporarily paralyzed, which is believed to be the body’s means of protecting you from acting out your dreams. As you age, less of your sleep time is spent in REM sleep.
The bottom line: While scientists continue to figure out how sleep and the brain affect each other, the important thing is to make sure you get enough of the good quality sleep you need to function at your best.
Not spending enough time in the most restorative part of sleep? We put together a list of easy ways to get more deep sleep.
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