Now a paper from Bar-Ilan University published Tuesday in the journal Nature Communications presents a groundbreaking theory: that when we sleep, our nerve cells take a break from their usual function, freeing their resources to reduce DNA damage that was accumulated during wakefulness. Sleep makes no evolutionary sense in that it’s an insanely vulnerable time for the slumberer. You’re more likely to get eaten by a predator than when you’re awake. So why would we evolve to need sleep?
It’s well established that loss of sleep affects brain performance such as memory and learning, from fruit flies to humans. This strongly argues that sleep is biochemically essential, and that sleep deprivation causes some kind of gradual systems collapse in the brain."