9 Facts About REM Sleep and Why You Need It

Sweet dreams—or should we say, sweet REM sleep? REM sleep is the phase of sleep associated with quick, darting eye movements, vivid dreaming, memory formation, and emotion processing. ¹ During REM sleep, our brain activity, breathing, and heart rate resemble our waking state more than during other stages of sleep. ¹

Every night, adults spend about 25 percent of their sleep in Rapid Eye Movement (REM) sleep. The remaining 75 percent of our time asleep is spent in NREM— non-rapid eye movement sleep. ¹

REM sleep is important for processing emotions, as well as learning, memory storage, and information processing, some of which also occur during NREM sleep. ² REM sleep may also help prepare you to wake up. ²

Every night, our brains cycle through periods of REM and NREM sleep. The first phase of REM sleep is about 90 minutes after you fall asleep. ² The shortest REM phase, it lasts only about 10 minutes. ¹ Each successive REM phase lasts longer, with the longest REM cycles occurring just before waking. ^1-3

While the other 3 stages of sleep are associated with the healing, growth, and regeneration of our cells, tissues, and immune system, REM sleep is all about the brain and connections between nerve cells. Specifically, REM sleep:

• Affects the processes that control how memory and learning work. ⁴
  
• Helps with memory consolidation—in other words, turn short-term memories into long-term memories. ⁵
  
  As we go through the day, the experiences we attempt to commit to memory are temporarily stored. During stage 3 (also known as slow wave sleep) and REM sleep, that information is encoded and transferred to long-term memory storage.
  
  

The stages of sleep include three stages of NREM sleep and one stage of REM sleep that repeat throughout the night in sequence.^{1, 3}

Each of the three phases of NREM sleep is characterized by changes in muscle tone, changes in heart rate, and a decrease in body temperature. Each phase of sleep also shows distinct changes in your brainwaves.^{1, 6}

Keep reading to learn more about each stage of sleep:^{1, 3}

Stage 1 is the lightest stage of sleep and transitions us from wakefulness to sleep. It is essentially the “falling asleep” stage and is very brief, lasting 5 to 10 minutes. Your eye movements, breathing and heart rate slow. Your brainwaves begin to slow.

In stage 2 sleep, you are lightly but fully asleep. Your eye moments slow and stop as your heart rate continues to drop. Your body temperature drops and your brainwave activity continues to slow, with brief bursts of activity. Stage 2 NREM sleep lasts up to 25 minutes.

This is the deepest stage of sleep. In deep sleep, your heart rate and breathing have reached their lowest, slowest points. At this stage it’s hard to be woken up. Waking from this phase of sleep may leave you disorientated and confused. There are no eye movements.

During stage 3 sleep, your body regenerates cells and tissues and grows new cells. The immune system is also working hard. It’s this stage of sleep that allows you to feel physically well-rested in the morning.

REM sleep is the last sleep stage before the cycle repeats. In REM sleep, you dream more than in NREM sleep—and more vividly—and your brain activity increases dramatically. The parts of the brain that coordinate input from our senses, govern emotions, and create memories are active during REM sleep. Your breathing rate increases as does your blood pressure and heart rate. Each of your later REM stages gets longer the more hours you’re asleep.^1,-2

Can you imagine what would happen if your body reacted to your wildest dreams? REM sleep takes care of that, immobilizing your skeletal muscles so that you don’t move while you dream. Most voluntary, skeletal muscles are paralyzed during REM sleep—muscles you need to live, of course, like the muscles that allow you to breathe and your heart to beat, remain active.

Getting to the REM phase of sleep requires passing through the NREM stages of sleep first, so it takes a full night’s worth of sleep to get enough REM sleep. Adults need to spend about 20 to 25 percent of their sleep time in REM sleep, broken up into 3 to 5 phases. Overall, adults need 7 to 9 hours of sleep—about 90 minutes of which need to be REM sleep.⁷

Because REM sleep comes in cycles, it’s broken up over the span of a night’s sleep. Typically, the final REM stage of the night ends not long before we wake up.^1,-2

Because of what happens during REM sleep – particularly in the brain – it’s so important to get enough REM sleep every night, so you can wake up refreshed and ready to go.

Not getting enough sleep, whether NREM or REM sleep, can and will definitely impact your overall well-being, beyond just feeling tired or sleepy during the day.

A lack of REM sleep is particularly associated with:

• An increased risk of weight gain. Decreased levels of REM sleep seem to be associated with lower levels of leptin, a hormone that promotes feelings of fullness.⁸
  
• Impaired procedural learning and memory. Our ability to learn and retain what we learn, such as a foreign language or motor coordination patterns, relies on REM sleep, and becomes more difficult when we get less of it.⁹

Waking up during REM sleep can lead to sleep paralysis, a temporary condition in which a person returns to wakefulness yet cannot move because their voluntary muscles are still “shut off.” Although sleep paralysis is not dangerous it can be scary or uncomfortable.¹⁰ Sleep inertia is also common-- it is the feeling of grogginess, disorientation, drowsiness, and cognitive impairment that immediately follows waking.^11,-12

REM sleep was first discovered and scientifically described in 1953.² Since then, sleep scientists have kept finding out more and more about this fascinating phase of our sleeping lives.

Here are some interesting facts about REM sleep you may not have known.

Establishing healthy sleep habits is essential to your overall health. Promoting a healthy lifestyle goes hand-in-hand with ensuring that you are not only getting enough sleep, but also getting quality sleep.

ZzzQuil is here to help you on your journey to your best sleep. Sign up for ZzzQuil’s Better Sleep in 1-2-Zzz to learn more about how you can optimize your sleep routine.