The brain’s nightly “Reset” process during sleep

What does the brain do while we sleep? New research shows the process that occurs within the brain during sleep

Sleep can have a crucial role in learning and memory. While we are awake, connections between cells in our brains get stronger. Sleep is important because if these connections continue, they become energetic. If too many connections are made in one day, fewer will be made the following day. 

Lead author Professor Jason Rihel, from UCL’s Cell & Developmental Biology department, explains, “While the function of sleep remains mysterious, it may be serving as an ‘off-line’ period when those connections can be weakened across the brain, in preparation for us to learn new things the following day.”

Activities within the drain during sleep-wake cycles 

The study used translucent zebrafish, allowing researchers to observe and monitor the complex activity within their brains across multiple sleep-wake cycles. 

They discovered during periods of sleeplessness, brain cells formed more connections, but during sleep, these connections were selectively weakened.

Dr Anya Suppermpool, the first author of the study, elaborates, “Our findings add weight to the theory that sleep serves to dampen connections within the brain, preparing for more learning and new connections again the next day. 

“There are other theories around sleep being a time for clearance of waste in the brain, or repair for damaged cells — perhaps other functions kick in for the second half of the night.” 

Importance of sleep in brain renewal 

If similar patterns hold in humans, it suggests that the timing and duration of sleep play a crucial role in optimising the brain’s ability to learn and adapt.

“If the patterns we observed hold true in humans, our findings suggest that this remodelling of synapses might be less effective during a mid-day nap when sleep pressure is still low, rather than at night when we really need the sleep,” says Professor Rihel.  

Understanding the relationship between sleep and brain function has important implications for human health and well-being. By solving the mechanisms underlying sleep, researchers may find new strategies to improve cognitive function, treat sleep disorders and improve overall brain health.  

This study makes it clear that a good night’s rest is not only essential for physical rejuvenation but also for mental clarity and learning.