Why do we Sleep?

We spend around a third of our life sleeping. Sleep is very important for our mental health as well as physical health. Sleep helps to repair and restore our brains overnight. Scientists think that during sleep our brains process information and secure memories. There are lots of things the brain does during sleep that let us function properly during the day. It is therefore important to get enough sleep. It is also important that the sleep we get is of a good quality.


There are lots of things about sleep that scientists are still trying to figure out. But we do know that there are two processes happening in the brain that contribute to sleep:

1 – Chemical

When we are awake, we build up a ‘sleep debt’ which is ‘repaid’ when we sleep.  This process is regulated by chemicals in the brain which build up when we are awake. Normally, this debt is paid off every night when we sleep. This means that the chemical build up is broken down. However, if we under-sleep for several nights then this debt has to be paid off over a longer time.

2- Internal clock

There is a part of the brain that works as an ‘internal clock’. It receives information from the eyes about how light it is in the outside world at that point in time. It uses this information to make a regular pattern controlling when we feel sleepy and when we don’t. When there is less light at night, for example, the internal clock tells us that we should sleep. This pattern repeats every 24 hours.


How much sleep we need varies from person to person. Adults tend to sleep between seven and eight hours per day. Older adults tend to sleep slightly less, but nap more during the day. It is very important to have a regular routine, so that the processes above will work the best they can. This means that we will feel awake when we need to during the day. We will also feel tired when we need to sleep at night.


When we sleep too much or too little, our mental health will be negatively impacted as well as our physical health. This will affect our thoughts, emotions, and behaviours. People who sleep less are more likely to suffer from a low mood. They are also more likely to develop a mental illness.

This means that it is important to monitor your sleep pattern. You can try the following things to improve your quality of sleep:

  • Don’t look at screens (such as a phone) for one hour before bed
  • Cut down on caffeine by drinking less tea and coffee
  • Don’t nap during the day
  • Try to relax before bed
  • Don’t eat or drink too much before going to bed

There are other things that you can do to sleep better, but if you are not succeeding, you should talk to a doctor about how to improve your sleeping pattern.


Sleep is a very important process. Improving the way we sleep can have a big impact on our mental and physical health. By taking some simple steps, we can have a positive impact on our mood and improve our ability to think clearly during the day. Whilst sleep seems simple and effortless, good sleep really can make a big difference to our lives.



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