The Difference Between REM and Deep Sleep


  1. What is REM?
  2. What is deep sleep?

All sleep is not the same. You’ve probably heard about light sleep and deep sleep, and many often equate deep sleep with REM sleep. Just as light and deep sleep are different from one another, REM and deep sleep are two completely different stages of the sleep cycle, each with defining characteristics. In all, there are five different stages of sleep, all of which contribute to your body’s circadian rhythm, or natural body clock. REM and deep sleep are stages three and four. 

What is REM?

Rapid eye movement (REM) sleep is the deepest sleep stage. The eyes move more rapidly in all directions during REM sleep, as its name indicates. REM is the fourth stage of sleep.

Time: REM sleep occurs approximately 90 minutes after you fall asleep.

Body: Your heart beats faster, and your heartbeat will likely become irregular during REM. Aside from this, the body is largely inactive during this sleep phase.

Brain: REM sleep cycles are associated with intense brain activity.  This is the stage where you’ll likely experience active and vivid dreams. Sleepwalking and bedwetting incidents occur only during REM. REM sleep restores your brain and is important for your learning as well as your long-term memory. 

Length: There are different periods of REM sleep, the first lasting about 10 minutes. There are about three to five periods of REM stages per night. The length of REM stages increase throughout the night, and the final stage can be up to an hour.

What Is Deep Sleep?

Deep sleep is non-rapid eye movement (NREM) sleep. There are three other NREM stages as well. Other names for this deep sleep stage are slow-wave sleep, delta sleep, and N3 since this is the third stage of sleep.

Time: The body enters deep sleep anywhere from a half hour to 45 minutes after falling asleep.

Body: Unlike REM, deep sleep is known for the changes in your body rather than your brain. Your breathing slows and your heart rate is regular during this stage. The muscles in your body become completely relaxed, and you typically sleep through external sleep distractions such as loud noises. Deep sleep is extremely important to overall health because it’s during this phase when the body naturally heals itself. Your body replaces cells, heals wounds, and builds muscle tissue, all while you’re sound asleep in bed.

Brain: There are almost always no dreams during this period of sleep. Although generally unlikely, if you do find yourself waking up during deep sleep, you’ll feel groggy and disoriented at first. It is during light sleep that you wake up the easiest. The Pod uses a Thermal alarm that gradually warms or cools your bed to gently wake you up feeling refreshed. 

Length: Deep sleep usually lasts anywhere from 1-2 hours, or 20-25% of your overall sleeping time. Some people may need more deep sleep than others as every sleeper is different.

In order to get your best sleep yet, you’ll need a sleep tracking product, like the Eight Sleep Pod that analyzes your nightly sleep data and tells you exactly how much sleep you’re getting in each stage. Sleep trackers allow you to pinpoint your sleeping patterns and compare this information to how much time in each sleep stage your body actually needs for a good night’s sleep. By following the simple steps sleep trackers suggest such as avoiding caffeine before bed, you can help regulate your sleep and improve your overall sleep health.

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