Sleep is considered the "brother of death". A believer ends their day with prayer and dhikr to seek Allah's protection until morning.
Surahs to Recite Before Sleeping
The Prophet (PBUH) used to recite Surah Al-Ikhlas, Al-Falaq, and An-Nas, blow into his hands, and rub them over his body. Reciting Ayatul Kursi also provides protection from evil throughout the night.