6 Dreamy Facts About REM Sleep

Love dreaming? You can thank REM for that.

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While the jury may still be out on what dreams mean, we do know that most people experience this strange phenomenon nightly while they sleep—and that it’s often during a stage of sleep called rapid eye movement, or REM sleep.

What Is REM Sleep?

In general, there are four stages of sleep: Stages 1, 2, and 3, and then REM sleep. Stages 1 through 3 are all considered “non-REM sleep.” You cycle through all stages of sleep several times a night, with deeper periods of REM near morning time. Here’s what happens in each stage of sleep:

  • Stage 1 is the changeover from wakefulness to sleep, which is generally light sleep. In stage 1, your heart rate, breathing, eye movements, and brain waves begin to slow down.
  • Stage 2 is a period of light sleep that occurs right before you enter a deep sleep. Brain wave activity continues to slow, but is marked by brief bursts of electrical activity.
  • Stage 3 is deep sleep—and what you need to feel refreshed and energized in the morning. It’s at this stage that your bodily functions are at their slowest. In fact, during this stage of sleep your muscles are so relaxed, it’s difficult to wake you.
  • REM sleep occurs around 90 minutes after you fall asleep, and makes up for about 25 percent of your snooze session. It’s called “rapid eye movement sleep” because your eyes do just that: Move rapidly from side to side. Other bodily functions, like your heart rate, breathing, and brain waves are heightened during REM sleep—close to what they are when you’re awake.

All sleep stages are important for optimal health, but REM sleep is so much more than just rapid eye movements. Here are some wild and dreamy facts about the amazing stage of sleep we call REM sleep:

1. Dreams are most vivid in REM sleep. You spend about two hours dreaming each night, but may not remember most of what you dream about. Dreams are experienced in all stages of sleep, but they’re much more lucid during REM sleep—which is likely the part you *do* remember. Another fun fact: Some people dream in color, while others dream in black and white.

2. During REM sleep, your brain may still “see.” When you move your eyes during REM sleep, new images may still form in your mind’s eye, according to a study published in the journal Nature Communications. This means your brain may still process the eye movement as seeing something, much like it does when you’re awake. So, in a sense, you may actually be “looking” at things in your dreams.

3. Your arms and legs are “paralyzed” during REM sleep. This prevents you from acting out your dreams, since they’re so vivid during REM sleep.

4. Alcohol can rob you of REM sleep. It’s a myth that a nightcap helps you sleep. It may help you fall asleep initially, but the quality of your sleep may suffer. A not-so-restful night’s sleep is just one of the many consequences of drinking too much before bedtime. Alcohol affects your sleep in many ways, but one of the reasons you feel tired in the morning is because it robs you of REM sleep. Because like deep sleep, REM is considered a restorative sleep stage. (Here are other alcohol myths to stop believing.)

5. REM sleep may help you solve new problems. Stumped on a problem? Sleep on it … literally. According to researchers at the University of California, San Diego School of Medicine, REM sleep may enhance your ability to solve issues creatively—more so than the other three sleep stages. The UCSD researchers found that for problems a person has already been working on, REM sleep seems to help the brain make new and useful associations between unrelated ideas.

6. People with narcolepsy experience aspects of REM sleep when awake. Narcolepsy is, in short, uncontrollable daytime sleepiness. But it’s more than just yawning a lot through class. If a person with narcolepsy is triggered by a strong emotion, like laughter, it may cause them to collapse and experience arm-leg paralysis similar to that of REM sleep. A person with narcolepsy may also experience dream-like hallucinations while falling asleep or waking up.

Looking to log more precious REM sleep? Here are 11 doctor-recommended ways to sleep better tonight.