Stages of Sleep

by | Dec 22, 2021 | Sleeping Science

Your brain and body are constantly in an active state, even when you’re not awake. While you are fast asleep and blissfully unaware, you are on a rollercoaster ride through the distinct phases (or stages) of sleep.

Each sleep phase has a different role to play in how you feel when you wake. This post explains which stage helps to restore your body, which will support your brain, and whether you are striking a good balance between these stages when you sleep.

What Are the Stages of Sleep?

Conventionally, your sleep cycle is characterised by four distinct phases: awake, light, deep, and REM sleep. Each type plays a vital role in sustaining your mental and physical health.

In essence:

  • REM sleep means “rapid eye movement” and is sometimes called “stage R”
  • Light and deep sleep are usually grouped together as NREM – “non-rapid eye movement” sleep or simply “stages 1-4”

What Does Each Stage Do?

Each stage or phase plays a unique role in preparing your body for the following day.

What Does a Normal Night Look Like?

The amount of each phase of sleep can vary significantly – no one person (or in fact one night’s sleep) is the same as another. Ideally, your body has enough time to go through four to five 90-minute cycles that cover the separate phases of sleep progressively.

For most people, each 90-minute cycle moves sequentially through each stage of sleep: wake, light sleep, deep sleep, REM, and repeat. As you doze, earlier cycles tend to have more deep sleep while later cycles have a higher proportion of REM. By the final cycle, unknown to you, your body may choose to skip the deep sleep phase completely.

Overall, your body spends 45-55% of the time in light sleep. REM or deep sleep phases can vary significantly but on average, you can expect to spend between 13-23% of your slumber hours in the deep sleep stage, and 20-25% in REM sleep.

Tips for Improved Sleep

All the stages of sleep are essential, and under normal circumstances your body will naturally regulate your sleep cycles to make sure you get what you need.

Tools like an Oura Ring or other sleep monitoring apps can help you gauge your sleep patterns and create a Sleep Score each night to help you improve your sleep.

These patterns will alert you if your sleep is being disrupted:

  • Increase in deep sleep after a hard workout: Exercise can increase your body’s prioritization of deep sleep after a rigorous workout. 1
  • Higher REM rebound after sleep deprivation: If you are in recovery from a period of sleep deprivation, your body will prioritize deep sleep for the first few nights. This helps to repair your body and prepare for action. After the required sessions of enough deep sleep, REM sleep rallies to focus on your brain.
  • Interrupted sleep cycles after caffeine: Caffeine can increase the time it takes for you to fall asleep, thereby shortening your sleep period. Shorter sleep periods consequently cut down on your total REM sleep, as REM cycles are more likely to happen during your later sleep cycles.

By taking a close look at your sleep-time patterns (including heart rate and body temperature) and actively working to improve your sleep, you can face your days well-rested and less likely to need a daily caffeine boost.


  • Stutz, Jan, Remo Eiholzer, and Christina M. Spengler. “Effects of evening exercise on sleep in healthy participants: A systematic review and meta-analysis.” Sports Medicine 49, no. 2 (2019): 269-287.
  • Adapted from an article on