What happens to your body when you are sleeping?

The importance of getting a good nights sleep

Updated: Thursday 15 April 2021

sleeping and your health and fitness

There are many things we don’t know about sleep. One thing is confirmed though – we need to sleep so our minds are rejuvenated in order to function throughout the day. We’re regularly told that we should be getting on average 8 hours of sleep per night and it’s important to get enough of it, as sleeping impacts our quality of life.

We’ve examined what happens to our body at every stage of your sleep cycle. Sleep is divided into two broad stages – non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. As we start falling asleep, we enter the NREM sleep and this lasts for around 75% of the night.

NREM Sleep

Stage 1 (1-7 minutes bursts)
When you are awake and just beginning to fall asleep. At this stage, as you are lightly sleeping you and can easily return to being awake.

Stage 2 (10-25 minutes bursts)
You have started to lose touch with your surroundings and have descended into a light sleep where your body temperature starts to drop, breathing slows down.

Stage 3/4 (Main cycle)
Your muscles have started to relax even more and by now you should be in your most restorative sleep. At this stage, the blood supply to your muscles have increase and tissue growth and repair occurs. By this point, you should be at your deepest stage of sleep where your body released growth hormones for growth and development and muscle development.

REM Sleep

This account for around 25% of the night and first occurs 90 minutes after you have fallen asleep. If you are on average getting 8 hours of sleep, you would typically experience 3-5 REM periods during the night. During REM sleep, your brain and body become energised, your heart rate starts to rise, breathing becomes quicker and blood pressure starts to rise. At this stage you typically start to have dreams and your eyes start to quickly move back and forth (hence the name REM). Your muscles are temporarily paralysed so there’s no movement in your arm or leg muscles to prevent you from acting out whilst you are dreaming.

The duration of each stage varies at different ages. You will find that an infant’s sleep cycle will be completely different of an adult’s or elderly people. However, what is common for all is that everyone goes through the same cycle in an orderly fashion.

The Importance of Sleep

Sleep is essential, we spend between one quarter and one third of our lives sleeping so it’s vital that we get enough sleep so improve our mental and physical well-being.

  • Sleeping the recommended amount every night reduces the risk of heart disease and stroke.
  • Sleep improves your immune function and helps to fight cold and flus.
  • When you don’t get enough sleep regularly, you will find yourself feeling more drowsy, short-tempered and sometimes depressed.
  • Sleep helps with your learning and memory as it helps you to focus more and sharpens the mind.
  • Sleep deprivation causes our bodies to alter our hormone levels which affect our appetite and changes the way our bodies store and process carbohydrates therefore triggering weight gain.

Toby Watson

Written by: Toby Watson

Pharmica Medical Writer

Toby (BSc) is an experienced medical writer, producing educational articles on many areas of health including sexual health, fitness, nutrition and mental health.

He particularly enjoys debunking misconceptions around heath conditions and their treatments, researching each topic in detail and writing easily-accessible content.

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