Question: How does sleep effect brain activity?

Alex Reid answered on 13 Nov 2018: last edited 14 Nov 2018 10:49 am

Hi Catherine, thanks for the fantastic question. When you sleep it might look like you are ‘vegged out’ and not doing much, but actually your brain is surprisingly active! In fact one sleep stage, known as Rapid Eye Movement (REM) sleep, is so active it looks very much like wakefulness, which is why people sometimes call it ‘paradoxical sleep’ (the paradox being that your body is asleep but your brain looks kind of awake). To answer your question more specifically here is a brief rundown of the different sleep stages: stage 1 sleep is usually a very short period when you drift off, and some of your brain activity diminishes. Stage 2 sleep is when you get little electric events between populations of brain cells called ‘sleep spindles’. This may be when parts of your brain are talking to each other and swapping information. Slow Wave Sleep (SWS), which also has spindles, is when your brain cells start synchronizing and firing together to create really large and slow moving brainwaves, this stage is also known as deep sleep. Lastly, you have Rapid Eye Movement sleep, which is the sleep stage most associated with dreaming. All these stages have different levels of hormones as well, some of which help your brain cells become more ‘plastic’ and open to changes. These sleep stages, although they look distinct, are often very fluid and will sometimes ‘flow’ into each other. In doing so they may work together to do a number of things, including memory processing, which is what I look at! The various types of brain activity between these stages is so recognizable we can look at many non-human animals and tell what sleep stages they are in too! For example, here is a cool video of some ostriches getting different types of sleep (they have sensors on their heads which are hard to see in the vid): https://www.youtube.com/watch?v=0EnDTs-1M14