Your brain and body during sleep

What happens during sleep?

While you are sleeping, there are a lot of things happening in the body – everything slows down and enables you to rest and restore every single part of it. Naturally, this happens in various stages. In essence, sleep cycles between REM sleep and non-REM sleep.

The meaning of REM is rapid eye movement. This means that while you are sleeping, your eyes shift from the left to the right in a fast manner, but they do not send any visual info to your brain.

If you want to know how the sleep cycle happens, first comes the non-REM sleep, then comes the REM sleep, and this is a cycle that repeats several times during the night. When you are dreaming, this means that you are in a REM state.

When you are in non-REM sleep

Before reaching REM sleep, the body goes through a few stages of non-REM sleep. Usually, these stages last for a period of about 5 to 15 minutes each, before the body changes into the second stage. Here is what happens 1,2:

  • First stage – your eyes are closed and you start to fall asleep, but it is easy to wake up. This first phase tends to last about 5 to 10 minutes, not more.
  • Second stage – the second stage happens when your body starts sinking into a light state of sleep. The body temperature drops and the heart rate slows down. This means that the body has prepared itself for a night of sleep. This is a stage that can last for about 10 to 25 minutes.
  • Third stage – is also known as the deep sleep stage. This means that you have entered a state of complete sleep, and it might be harder for someone to wake you up. Also, if they manage to do so, you will feel a bit disoriented for a while, until all body functions go back to normal.

Once the body enters the deep sleep stage, it starts regenerating. All the tissues, muscles, and bones begin to repair and regrow – which ultimately leads to an improved immune system. It has been proven that as the body gets older, you will need less sleep and experience less deep slumber.

When you are in REM sleep

REM sleep happens about an hour and a half after you have fallen asleep. The first period of this cycle lasts for about 10 minutes or so. As you go deeper into the stages, each one lasts more than the previous one. The final stage may even last up to an hour. This is when your breathing and your heart rate accelerate.

It is normal to experience some intense dreams during this stage of the sleep cycle since the brain is very active then. This is an important part of the sleeping process because it can stimulate the area of the brain that has difficulty learning and is connected to increased protein production.

Hope you find this info helpful and valuable! If you want to read more on this subject head on to our blog page and contact page and find out more!

  1. National Institute of Neurological Disorders and Stroke. (n.d.). Brain basics: Understanding sleep. Retrieved June 7, 2017, from
  2. National Sleep Foundation. (n.d.). What happens when you sleep? Retrieved May 1, 2018, from
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