could someone eli5 this for me pls.
Much like you occasionally reboot your machine to flush and re-align memory etc...
When you sleep, your sensory input systems are handed a surrogate (dreams) whist the rest of your brain gets back into phase with itself, and the idea is that this allows for an 'alignment' of sorts within the brain which allows for the cerberal fluids to more porously flow through the brain and carry away ionic and other molecules which freely float through the brain.
As the rain washes the paths and the streets after a windy, dusty day...
To allow for a fresh path where the previous wake-cycles experiences in molocules can be more properly absorbed into the brain and your neurons can 'take in' what happened all wake cycle.