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Why we need REM sleep for health

December 13, 2023 | Heather Shannon
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If you’ve spent enough time in REM sleep, you’ll wake up feeling refreshed and alert.

A good night's sleep is about more than how long you slumber. The quality of your Z’s matters, too.

While you sleep, your brain is active, producing electrical patterns that change throughout the night.

Those patterns are divided into four stages of varying duration and depth, UCI Health sleep medicine expert Dr. Rami N. Khayat explains.

One of the most critical stages is called rapid eye movement, or REM, because of the characteristic eye activity in this sleep cycle.

Benefits of REM sleep

During this 90- to 110-minute stretch of dozing, emotional experiences are processed and memories are consolidated, recent research has shown. The brain also rests and repairs itself.

If you’ve had enough REM sleep, you’ll wake up feeling refreshed and alert. It is also associated with better mental health and a stronger immune system.

As much as researchers know about this important sleep phase, REM is still not fully understood.

“There are likely other functions for REM sleep and other sleep stages that we will learn in the future,” says Khayat, medical director of UCI Health Sleep Medicine Services.

Changing REM needs

The amount of REM sleep needed for optimal functioning is at its highest before we’re even born.

Fetuses sleep most of the time and cycle between REM and non-REM stages. Newborns sleep about 16 hours a day, half of it spent in REM.

By early childhood and thereafter, Khayat says, the REM stage accounts for about 25% of a total night’s sleep.

Experts recommend that a healthy adult get seven to nine hours of sleep a night. Of that, REM should account for an hour and 45 minutes to two hours and 15 minutes.

An individual's sleep and REM patterns can temporarily change, such as after a bout of sleeplessness, Khayat says. Too much REM sleep also is a problem, and it’s often a sign of another issue, such as depression.

Improving REM sleep

Genetics, health conditions and individual lifestyles all factor into how much REM sleep a person may get.

The single best way to get the benefits of REM is to sleep long enough for it to occur. REM is typically more concentrated in the latter half of the 90- to 110-minute cycle.

However, what we eat and drink and the drugs we take can affect the quality of the rest we get, notes Khayat, a professor of pulmonary and critical care medicine as well as psychiatry at the UCI School of Medicine.

Both over-the-counter and prescription medications can interfere with sleep cycles.

“Many medications — including commonly used antidepressants and, counterintuitively, many sleep aids — can decrease REM sleep,” he says.

Consuming alcohol or caffeine close to bedtime can also disrupt REM sleep.

“The more we provide our brains with the right space and time and decrease exposure to extraneous substances and medications, [the more] it will function normally, and produce REM sleep that helps us process and consolidate memories and emotions,” Khayat says.

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