Sleep Cycle Stages – What happens While You Sleep

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Sleep Cycle Stages

When we sleep, we typically go through several cycles of sleep. And each one of these stages consists of 4 different stages of sleep. Let’s take a trip through Sleepy Town and go through the differences of these stages and what we know about each of them.


This stage occurs after you have decided to sleep and your eyes are closed.

  • Breathing gradually becomes more regular and the heart rate begins to slow.
  • This is the time where you get that crazy feeling that you are falling and twitch awake.  
  • A person awakened during this period will often believe they haven’t slept.

Fun fact of the day: this twitch is called a hypnagogic jerk, and are quite common.


This sleep stage refers to the combined stages of what was previously separated into Stage 3 & 4 sleep.

  • This stage typically starts 35-45 minutes after falling asleep.
  • As electroencephalograms show, our brain waves slow down and become larger
  • At this point, you sleep through most potential sleep disturbances (noises and movements) without showing any reaction.
  • If you actually wake up during NREM Stage sleep, there’s a high probability you are going to feel disoriented for the first few minutes.
  • Other names for this stage include “slow-wave sleep” and “Delta sleep.”


 When NREM Stage 2 sleep kicks in, things get serious!

  • Stage 2 sleep, which usually lasts about 20 minutes, is characterized by a slowing heart rate and a decrease in body temperature.
  • Your body reduces its activity to prepare you to go into a deep sleep.
  • Your blood pressure, as well as other metabolic functions, slow down.
  • It becomes harder to wake you up.
  • Your brain starts to emit larger waves.

The 2 first stages of NREM Sleep together are often referred to as light sleep. 


This is the final stage of a standard sleep cycle. The first Rapid Eye Movement sleep stage lasts around 10 minutes and usually happens after having been asleep at least 90 minutes.

  • As its name indicates, your eyes move rapidly in all directions during Rapid Eye Movement sleep.
  • It is during this stage of sleep (the deepest) that powerful dreams usually happen. Same goes for sleepwalking and bedwetting episodes.
  • This stage is also characterized by an increase of the heart and respiration rates, and their rhythms may become irregular.

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