Clearing waste from the brain during sleep may make the brain more efficient and reduce its energy consumption.

“I was reading recently about this glimpmphatic clearance of waste in the brain that occurs during sleep and uh there was an interesting figure in this paper showing that Every mammal puts its head down during sleep. And there's some cute pictures of pandas sleeping on their side. The giraffe apparently puts the top of its head down uh in order to presumably increase lymphatic clearance. But I could also imagine that resting one's head reduces energetic demands.”

“Interestingly, this similar thing happens where the spaces between your brain cells actually increases and like sort of like a like actually like a like a filter the it increases and actually waste products can start clearing out of your brain.”