Abu Huraira reported God’s Messenger as saying, “When one of you goes to sleep the devil ties three knots at the back of his neck, sealing every knot with, ‘You have a long night, so sleep’. So if one awakes and mentions God a knot will be loosened, if he performs ablution a knot will be loosened, and if he prays a knot will be loosened, and in the morning he will be active and in good spirits; otherwise he will be in bad spirits and sluggish in the morning.” (Bukhari and Muslim.)