What Are the Stages of Sleep: REM and Non-REM Sleep Cycles?

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

If you’ve ever wondered how many stages of sleep are there, the answer is four. These include 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 blog, we’ll walk through each stage, look at what are the stages of sleep, and share tips for getting better-quality rest.

You can 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?

Sleep is divided into two main types: 

1. Non-REM (NREM)

2. REM (Rapid Eye Movement)

A full night’s sleep cycles through these stages multiple times, each cycle lasting about 90 minutes.

You may be familiar with REM sleep, the stage where your brain becomes more active, and dreams occur. But if you’ve ever asked yourself how many stages of sleep are there, the answer is four. Each of these stages plays an important role in how our bodies experience and benefit from 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 sleep stage is Non-REM Stage 1 sleep, or N1 sleep. It is the bridge between being awake and asleep. It lasts just 1–5 minutes. Your eyes may feel heavy, your brain starts to slow down, and your body begins to relax.

If you’ve ever jerked awake just as you’re drifting off, yep, that’s your body in Stage 1. It’s quick, and unless you’re interrupted, you’ll slide into Stage 2 pretty fast.

Stage 2 (Non-REM)

In Stage 2 (N2), your body really starts prepping for deep 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

This stage usually lasts 10–25 minutes, and it’s where you’ll spend the bulk of your night. Think of it as your body’s way of shifting gears down before heading into deeper sleep.

Stage 3 (Non-REM)

Stage 3, or N3, is what people often call deep sleep. It’s the stage that leaves you feeling refreshed in the morning. It is considered “deep sleep” because it is critical to achieving restorative sleep. 

Here’s what happens.

• Your brain produces delta waves (the slowest brain waves)

• Your body’s repair work kicks into high gear

• Growth and recovery processes peak

• Your immune system gets a boost

Stage 3 typically lasts 20–40 minutes, especially in the first half of the night. If someone wakes you during this phase, you’ll probably feel groggy or disoriented.

This is also where people often compare deep sleep vs REM sleep. Deep sleep is more about physical recovery, while REM is tied to brain activity, dreams, and memory. Both are equally important.

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. Here’s what happens in this stage:

• Your brain becomes active again

• Your eyes dart around (that’s where “rapid eye movement” comes from)

• Your body goes into atonia—temporary paralysis, except for your eyes and breathing muscles

• Dreams are most likely to happen

REM sleep isn’t just about dreaming; it’s crucial for learning, memory retention, and creativity. It can last just a few minutes or stretch to nearly an hour, and you’ll cycle through it several times a night.

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.

What External Factors Affect Sleep Stages?

Not everyone cycles through sleep in the same way. A few things can change how your body moves through these sleep stages:

• Age: Age is one of the factors that affects the stages of sleep. 

1. 1. 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. 

   2. Kids also fall into REM sleep much faster. Older adults, however, get even less REM sleep.

• Abnormal sleep patterns: A consistent bedtime supports the body’s internal clock. Irregular sleep or several nights of poor rest can disrupt normal sleep cycles.

• 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: Conditions like sleep apnea or restless leg syndrome interrupt sleep stages with frequent awakenings, preventing 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 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, several disruptions 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 down 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!