Stages of Sleep: REM & Non-REM Sleep Cycles

Sleep is a valuable part of the human existence—it’s the time for your body to rest and recover, repair systems, and retain information. In tandem with food, water, and shelter, sleep is an essential part of survival, and it’s a key element in maintaining your physiological and mental health. 

The full sleep cycle happens in four stages: Stage 1, 2, 3, and REM sleep. Each stage has its unique characteristics that collectively contribute to the rested and energized feeling you have after a good night’s sleep. In this post, we’ll explore each of these stages and the external factors that affect your sleep. Lastly, we’ll suggest some tips for improving the quality of your sleep.

Read on for a comprehensive overview of the stages of sleep, or use the links below to jump ahead to specific sections, like the REM sleep cycle or tips to improve your sleep.

• What are the stages of sleep?
• Stage 1 (Non-REM)
• Stage 2 (Non-REM)
• Stage 3 (Non-REM)
• REM Sleep Stage
• External Factors Affecting Sleep Stages
• How to Improve Your Sleep
• Takeaways

What are the stages of sleep?

You’re probably most familiar with REM sleep, the stage where your brain becomes more active, and dreams occur. However, there are actually four stages that each play an important role in how our bodies experience sleep. Let’s take a look at how the National Sleep Foundation breaks down each sleep cycle and its importance.

Stage 1 (Non-REM)

The first stage of sleep is Non-REM Stage 1 sleep, also known as N1 sleep. In this phase, our bodies start to transition from wakefulness to sleep. This period usually lasts 1-5 minutes; during these few minutes, your body and brain activity begin to slow down and you start to feel drowsy. Moving from Stage 1 to Stage 2 can happen pretty quickly if there’s no disruption.

Stage 2 (Non-REM)

In the second stage of sleep, your body gets ready to rest:

• Body temperature begins to lower
• Heart rate slows
• Muscles relax 
• Eye movement stops
• Brain activity starts to slow, but with random bursts of activity

The N2 phase generally lasts between 10-25 minutes.

Stage 3 (Non-REM)

Stage 3 (N3) is considered “deep sleep” because it is critical to achieving restorative sleep. In Stage 3, your physiological functions continue to slow and your brain starts to form delta waves, which are the slowest frequency brain waves. Stage 3 sleep is most often associated with restorative sleep, growth, and recovery. Sleep scientists also believe that Stage 3 sleep plays an important role in bolstering the immune system. N3 Sleep generally lasts 20-40 minutes. 

REM Sleep Stage

Rapid eye movement (REM) is the fourth sleep stage, but it’s usually the one people are most familiar with. During REM sleep, your brain becomes active once more. Meanwhile, your body goes into “atonia,” which is a type of temporary paralysis that affects almost the entire body, with the exception of your breathing muscles and eyes, which move rapidly during REM sleep.

REM sleep is important for several reasons. For one, it’s the stage in which you’re most likely to dream, but it also plays a key role in cognitive functions, such as memory retention, learning, and creativity.

Generally the REM stage sets in after you’ve been asleep for around 90 minutes and it only lasts between a few minutes and up to one hour.

External Factors Affecting Sleep Stages

It’s important to note that while these four sleep stages are typical of the general adult population, there are some factors that can impact an individual’s sleep stages.

Age

Unlike adults who spend around 25% of their sleep in the REM cycle, infants and children up to five years old spend most of their time sleeping in the REM stage. Plus, they are more likely to fall asleep and enter the REM cycle right away. Elderly adults, on the other hand, spend less time in REM sleep.

Abnormal sleep patterns

If you’ve ever searched for tips to improve your sleep, you’ve likely been advised to stick to a regular bedtime. This can help your body’s internal clock set a pattern for when and how long you sleep. This pattern is easily influenced, so if you get a few nights of poor sleep in a row, it can establish a new, abnormal cycle.

Alcohol

Alcohol can also alter your body’s regular sleep cycle by delaying the REM cycle. When the alcohol starts to wear off, your body may re-enter REM later.

Sleep disorders

There are several sleep-related disorders that can change how your body moves through the four stages of sleep. Sleep apnea and restless leg syndrome, for example, both cause frequent awakenings throughout the night. As a result, you might not be able to keep up a healthy sleep pattern.

In addition to sleep-specific disorders, nighttime acid reflux symptoms, shoulder pain, and other conditions can also cause disruptions while you sleep. These external factors can substantially alter the architecture of your sleep—sometimes, they improve naturally and other times, you may need to initiate some changes. 

How to Improve Your Sleep

Achieving a good night’s sleep is important to your physiological and emotional wellness, but it’s not always guaranteed. From physical discomfort to noise and light pollution, there are plenty of things that can disrupt the different levels of sleep and negatively impact the overall quality of your sleep.

In this section, we’ll take a look at some methods you can try to improve your sleep.

Practice positive sleep habits

• Set a nighttime routine
• Try not to use blue light devices before bedtime
• Exercise earlier on in the day rather than right before bed

Improve your sleeping environment

• Set your thermostat to 65°F—the ideal sleeping temperature, according to the National Sleep Foundation.
• Minimize light and noise pollution by installing blackout shades or curtains.
• Invest in quality bedding to ensure you’re comfortable and supported.

Address physical discomfort

Sometimes the reason we can’t get to sleep at night is simply because we’re uncomfortable. From imperfect pillows and tangled blankets to more serious medical issues, there are several disruptions that can come between you and a good night’s rest. Here are a few tips to help address physical discomfort and improve the quality of your sleep.

• If you deal with acid reflux at night: Try sleeping in the best sleeping position for acid reflux, elevated on your left side. MedCline’s Reflux Relief System is designed to help you sleep in this physician-recommended position more comfortably.
• If you have neck pain at night: Avoid using a pillow that is too tall or too stiff and make sure your spine is aligned by using a pillow that keeps your neck more elevated than your head.
• If you have shoulder pain while you sleep: Try not to put too much pressure on your downside shoulder by elevating your head and neck. The Shoulder Relief System from MedCline alleviates shoulder pain by lifting your body weight off of your downside arm and allowing it to rest comfortably in a built-in pocket.

Takeaways

• There are four stages of sleep:
• Stage 1 (N1)
• Stage 2 (N2)
• Stage 3 (N3)
• REM
• Each stage of sleep contributes to the overall restorative feeling you get when you wake up from a good night’s sleep. 
• There are several external factors, including age and sleep-related disorders that can influence your body’s sleep cycle.
• By practicing good sleep habits, investing in your sleep environment, and addressing physical discomfort, you can improve the quality of your sleep. 
• If you’re dealing with physical discomfort while you sleep, you can turn to therapeutic products such as MedCline’s Shoulder Relief System and Reflux Relief System for help targeting these issues.

Talk to a Sleep Specialist or visit our FAQ page to learn more about how MedCline can help you improve the quality of your sleep and general wellness today!