John Piper brings theology to bear on our sleep:
Sleep is a daily reminder from God that we are not God. “He who keeps Israel will neither slumber nor sleep” (Psalm 121:4). But Israel will. For we are not God. Once a day God sends us to bed like patients with a sickness. The sickness is a chronic tendency to think we are in control and that our work is indispensable. To cure us of this disease God turns us into helpless sacks of sand once a day. How humiliating to the self-made corporate executive that he has to give up all control and become as limp as a suckling infant every day.
Sleep is a parable that God is God and we are mere men. God handles the world quite nicely while a hemisphere sleeps. Sleep is like a broken record that comes around with the same message every day: Man is not sovereign. Man is not sovereign. Man is not sovereign. Don’t let the lesson be lost on you. God wants to be trusted as the great worker who never tires and never sleeps. He is not nearly so impressed with our late nights and early mornings as he is with the peaceful trust that casts all anxieties on him and sleeps.