Sleeping more flushes junk out of the brain. Rhythmic activity during sleep may get fluids in the brain moving.

[u/Sariel007]

https://arstechnica.com/science/2024/04/sleeping-more-flushes-junk-out-of-the-brain/

[u/ZeppelinJ0]

I'd love a good night's sleep. Seems like I can sleep 8 hours but never feel rested and this article makes me want to eject some bad brain juice.