The Sleep cycle shows the different stages we go through as we sleep.

Non-REM (Rapid Eye Movement) stage 1

We start to feel drowsy in this stage, as our heart rate slows and body temperature drops. We are still aware of what’s going on around us and can be easily woken.

Non-REM stage 2

We fall in to a state of light sleep. We spend 50% of a night’s sleep in this stage.

Non-REM stage 3

We fall into very deep sleep. We are less likely to be woken by noise and will appear confused and groggy if we’re woken up. This is the time our body does repairs and builds up energy for the day ahead.

REM (Rapid Eye Movement) sleep stage 4

Our eyes move rapidly from side-to-side and we dream during this stage. While our brains become more active, our bodies relax and our arms and legs are still. 

About 20% of a night’s sleep is in this stage.