It was narrated that Abu Hurairah said: The Messenger of Allah (ﷺ) said: 'When any one of you goes to sleep, the Shaitan ties three knots on his head, saying each time: "(Sleep) a long night." If he wakes up and remembers Allah (SWT), one knot is undone. If he performs wudu', another knot is undone. If he prays, all the knots are undone and he starts his day in a good mood and feeling energetic. Otherwise he starts his day in a bad mood and feeling lethargic.'"