because of how we evolved biologically, there are some processes, particularly in the brain and not just the body, that can only happen during sleep like "garb

because of how we evolved biologically, there are some processes, particularly in the brain and not just the body, that can only happen during sleep like "garbage collection" ie. https://pmc.ncbi.nlm.nih.gov/articles/PMC4651462/ https://pmc.ncbi.nlm.nih.gov/articles/PMC4651462/