WHY DO WE SLEEP?

A good night's rest is an essential part of life, but getting enough can be hard. We take a look at the science behind snoozing and how you can sleep easy

- FRANCES DANIELS

It takes up a third of our lives and seems to be a non-negotiable part of being human, but what exactly is sleep and why is it essential?

Sleep is often defined as a state of rest, and it does appear that way from the outside. However, our brains and bodies are working overtime. During sleep, the brain and body go through a schedule of events known as sleep cycles. We typically go through six cycles per night, and each one is made up of four stages. Stage 1 is the period when you first doze off, and it lasts up to seven minutes. Stage 2 lasts for up to 25 minutes and is accompanied by muscle relaxation, a slower heart rate and a cooler body temperature. Next up is Stage 3, commonly known as deep sleep as it's difficult to wake up during this stage. It lasts up to 40 minutes and is essential for body recovery and growth.

The final stage is rapid eye movement (REM) sleep, because the eyes move quickly even though they're shut. REM doesn't occur until you've been asleep for at least 90 minutes and lasts up to an hour. Brain activity increases during REM sleep, so you're more likely to experience vivid dreams in this stage.