These things don't often go together, but they should. It's not just that the human body needs hours to repair itself physically – or at least minimize the amount of conscious hours where it might continue to break itself down – but that the dynamic busy-ness of this life, being pulled in so many directions, each of which requires mental exertion to the point of exhausion, while constantly juggling the existential questions of who am I, what am I doing here, and what will happen to me when it's over... it all requires processing. Sleep is the perfect time to do it, not only because it puts life on pause but because it allows you to dream. The subsconscious finally gets time to untangle your life, to reset you so you're ready to go back out into the fray the next day.