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According to the National Library of Medicine, sleep occurs in 5 stages. These are broken up into Wake, Non-REM sleep, and REM. Some experts combine 2 of these stages, so there are 4 total sleep stages. Either way, sleep is always divided into Non-REM and REM. Throughout the night you may pass through each stage multiple times, in a cyclical manner.
Each stage plays an important role in helping us feel rested and rejuvenated when we wake up. Let's explore the different sleep stages and what they do for us! In the article below you’ll learn what each stage is, and why it’s important. We’ll also look at factors that can impact the sleep cycle.
Let’s start with an overview infographic so you can visualize how these stages fit together.
The Wake stage is kind of like pre-sleep. During this time you start to feel drowsy. Your eyes start to close, and you feel more relaxed. This is the last bit of wakefulness before you start to drift off. You will also have occasional periods of wakefulness throughout the night.
Stage 1 doesn’t last long, only a few minutes. During this time it’s easy to wake back up. Essentially, you are “dozing off” in this stage. If you’re not awoken, you’ll move quickly into the next stage. Here are a few things your body will experience in this stage:
About half of your sleep during the night is in the N2 stage. This stage is marked by a decrease in brain activity and it usually lasts around 25 minutes. Your brain does important memory consolidation during this stage. You’ll also experience the following during this stage:
Another interesting part of this stage is that your brain displays bursts of activity called sleep spindles, which help you progress into deep sleep. You also experience K-complexes, which are short delta wave bursts. These K-complexes prepare your brain for the slow delta waves of deep sleep.
Stage 3 is the period of deepest sleep, also called slow-wave sleep, because of the slow delta brain waves. It’s difficult to wake up during this stage, and if you do wake up, you will likely feel groggy and experience sleep inertia. Because the body is so relaxed, issues such as sleep-walking or bed wetting can occur.
This stage is very important for brain & physical health. This is when our bodies do the most of their repair work, and it's essential for things like muscle growth, tissue repair, and energy restoration.
REM sleep is the most important stage of sleep, as it's during this stage that our body and mind rejuvenate. REM sleep is named for the rapid eye movement that occurs during this stage, and it's during REM sleep that we experience the most vivid dreams. Most people need around 90 minutes of REM sleep per night in order to feel rested and refreshed.
So what makes REM sleep so special? Well, during this stage, our brain is highly active and our body is essentially paralyzed. This combination allows our brain to rest and rejuvenate while our bodies are at rest. Here are some other ways our bodies act during REM sleep:
When our sleep cycle is disrupted, it can lead to a number of negative consequences such as fatigue, irritability, and difficulty concentrating. There are many things that can disrupt our sleep cycle, such as:
Your age also plays a role in your sleep cycle. Infants spend much more time in REM sleep. As you get older, you’ll spend less time in REM and Stage 3 Deep sleep.
Lack of sleep can cause problems with our mood, concentration, and overall productivity. It can also lead to health problems such as obesity, heart disease, and diabetes.
For tips on how to get better sleep, check out the Sleep Like Sasquatch Guide. If you are experiencing symptoms such as excessive daytime sleepiness, inability to fall asleep, or other sleep concerns, please see your doctor or sleep specialist.
