Which maintenance tasks, why does it require us to be unconscious, why can't we apply constant energy towards them? Lots of interesting questions to answer

Like memory consolidation and physical restoration. My lay understanding is that we are unconscious because we turn our sensors off during deep sleep, and direct energy away from the prefrontal cortex, where reasoning and consciousness reside, to the limbic system, which processes memories and feelings, so that learning can take place.

Mental and physical body process refactoring is my guess

Quiet, so as not to attract predators.