What happens when we sleep?
The stages of sleep
It’s important to understand a little about the science of sleep as it will give you a much better understanding of how we sleep and what supports good quality sleep.
Sleep does not act like a light bulb that is either on or off. There are four different stages of sleep that everyone goes through several times each night; varying from light to deep sleep.
These stages are made up of two types of sleep: REM (Rapid Eye Movement Sleep) and Non-REM.
Non-REM sleep
Non-REM sleep is made up of three stages. This is the restful and restorative sleep where your body is being repaired.
Non-REM sleep relaxes muscles and lowers body temperature, heart rate and blood pressure.
Stage N1 is where you experience light sleep, when you are nodding off but can be easily woken by a slight sound or movement.
Stage N2 is a deeper sleep, you are still aware of your surroundings but if left undisturbed you will continue to Stage N3.
Stage N3 (slow wave sleep) is when you are in a deep sleep and may find it difficult to awaken.
REM sleep
REM (rapid eye movement) is where the body switches off and the brain receives extra blood and processes the day’s events.
This helps support learning and the development of your social and emotional skills. In REM sleep you dream.
During this period of sleep your body is paralysed, so you don’t act out your dreams.
Sleep cycles
It usually takes us around 90 minutes to cycle through the stages of sleep. The diagram shows an example of how these cycles occur.
During the first third of the night we tend to have our deepest sleep. It is thought that this is the time when most of the body restoration and repair occurs.
Other aspects of sleep
Why has it got harder to get to sleep?
During your teenage years, your sleep cycle is different to when you are a young child or an adult. You may find yourself being called lazy or sloth-like, seemingly unwilling to get up in the morning when the alarm clock shouts. But… you are not lazy!
How well do good sleepers sleep?
In order to know whether or not we need to improve the sleep we’re getting, it can be helpful to know what getting good sleep might look like.
Page last reviewed: 7 February, 2024