You slap your cheek and roll down the window. You do something to try to drive the sleep away. You must be alert, you must be razor-sharp. You must not live as a spiritually drugged zombie. Stay awake, spiritually.
Physical sleep is a wonder.
It is a created power of God to cut you off from reality, from the reality of the world, from troubles, unpaid bills. Physical sleep cuts you off from reality. Your life, saved in Jesus Christ, is in Christ. The spiritual things of the kingdom of God are your sole concern. Life for you now is communion with Christ.