Each night you take a rollercoaster ride through the different phases of sleep. Though you’re unaware of what goes on while you’re snoozing, your brain and body are in an active state.

Each stage of sleep plays a different role in how you feel the next day. Read on to learn which stage helps your brain, which restores your body, and if you’re striking a good balance between the stages each night.

What Are The Stages of Sleep?

Sleep has been traditionally divided into 4 categories: awake, light, deep, and REM sleep.  Each one plays an essential role in maintaining your mental and physical health.

The stages of sleep are awake, light sleep, deep sleep, and REM Sleep.

Note: As you’re reading about sleep, you may also see the terms “NREM” or “Stages 1-4.” These are simply other terms for the phases of sleep.

  • REM sleep stands for “rapid eye movement” and can also be called “stage R”
  • Light and deep sleep can be grouped together as “NREM  – non-rapid eye movement” sleep or referred to as “stages 1-4”

What Does Each Stage Do?

Each stage of sleep plays a different role in preparing your body for the next day.

Awake time happens before and after falling asleep. It also includes brief awakenings during sleep.

During light sleep, your respiration slows, your heart rate decreases, your body temperature drops and waking up is easier.

Deep sleep promotes muscle growth and repair. It also flushes brain waste and shows long, slow brain waves.

REM Sleep supports your brain. During REM, vivid dreams occur and your body becomes immobile to stop you acting out your dreams. It also improves memory, learning, and problem solving.

What Does A Normal Night Look Like?

The amount of each phase of sleep can vary significantly between nights and individuals. During an ideal night’s sleep, your body has enough time to go through four to five 90-minute cycles that sample different phases of sleep as the night progresses.

In general, each cycle moves sequentially through each stage of sleep: wake, light sleep, deep sleep, REM, and repeat.  Cycles earlier in the night tend to have more deep sleep while later cycles have a higher proportion of REM. By the final cycle, your body may even choose to skip deep sleep altogether.

Deep sleep occurs more in the first half of the night while REM occurs during later sleep cycles.

Overall, your body spends the majority of the night in light sleep. How much time you spend in REM or deep can vary widely by individual but below are the averages you can expect for each stage in a single night.

It is normal to spend most of the night in light sleep.

Tips for Improved Sleep

All stages of sleep are important and your body naturally regulates your sleep cycles to make sure you get what you need.

Tools like the Oura Ring can help you monitor your sleep patterns and generate a Sleep Score each night to help you improve your sleep.

Check out these patterns to see if your sleep is being disrupted:

  • Increase in deep sleep after a hard workout: Exercise can increase your body’s prioritization of deep sleep the night after an intensive workout.1
  • Higher REM rebound after sleep deprivation: When you recover from a period of sleep deprivation, your body prioritizes deep sleep for the first few nights to repair your body and prepare for action. After several nights of sufficient deep sleep, REM sleep rebounds  to focus on your brain.
  • Interrupted sleep cycles after caffeine: Caffeine can increase the time it takes for you to fall asleep, cutting your sleep period short. Shorter sleep periods disproportionately cut down on your total REM sleep, as REM cycles are more likely to occur in later sleep cycles.

We all have those days when we “just need our coffee.” However, taking a look at your nightly patterns (e.g. heart rate, body temperature) and acting on your desire to improve your sleep can help you face those days well rested.

 

 


References

  1. 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.