What Happens to Your Brain When You Sleep

Although sleep is an integral part of our lives and vital for our survival, experts are still yet to understand exactly how and why it works and just what it does for us. What we do know so far is that several biological processes happen when we sleep, and many of those are crucial when it comes to maintaining healthy brain function. Here’s exactly what happens to your brain when you sleep…

According to a study conducted by the University of Rochdale, one of sleep’s primary functions is to undertake certain ‘housekeeping’ tasks such as removing toxic waste from the brain. During the day neurons consume high amounts of energy that are required by everyday tasks, thinking and other normal daily practises. A consequence of this exertion is that as they do this, they also eject a lot of debris, mostly consisting of leftover proteins, that then float around the brain. At night when we sleep, the brain’s in-house clearance network ­– called the glymphatic system – is triggered into action, becoming more active, and shrinking the glial cells, which play an important role in keeping nerve cells alive. When this happens it allows more space between brain tissue to open up, which in turn enables fluid to be pumped around and the accumulated toxic material to be washed away. As well as helping to improve cognitive function and memory consolidation amongst other things, experts believe this action is particularly important in helping to prevent age-related brain conditions such as Alzheimer’s disease, where proteins such as amyloids can build up and cause damage.

During the NREM stages of sleep (deep or “slow wave” sleep), the thalamus area of the brain becomes quiet, letting you tune out the outside world. This enables the brain to sort through memories from the day before and filter out important memories and eliminate the excessive ones which aren’t needed, and which could clutter the nervous system. As this continues these memories get converted from short-term to long-term memories. During the REM stages of sleep, our emotional memories are processed, allowing us to deal with difficult or traumatic experiences.

Another major role of sleep is its ability to contribute to neuroplasticity, essentially the process in which the brain adapts and reorganises itself to cope with everyday demands. A study carried out by the Humboldt and Charité Universities in Berlin discovered that during sleep, activity in a cluster of brain cells called the dendrites becomes heightened, a process which is linked to the formation of brain waves that helps form new memories. This process of regeneration and rejuvenation is critical because it allows our brains to change and adapt based on our experiences.

Adequate sleep isn’t just necessary for the physical health of our brain but for our mental and emotional health too. When we sleep, our brain activity increases in the amygdala, the area in the brain responsible for regulating and processing emotions. It’s the amygdala which helps to keep our emotions and moods stable on a daily basis. When we don’t get enough sleep on the other hand, the amygdala becomes prone to overreaction, causing our emotions to become heightened or exacerbated and us to feel and behave in an ‘overemotional’ way.