The dua before sleeping is: 'Bismika Allahumma amutu wa ahya' — meaning 'In Your name, O Allah, I die and I live.' The Prophet taught this as the supplication to recite when lying down to sleep, entrusting oneself entirely to Allah for the night.
بِاسْمِكَ اللَّهُمَّ أَمُوتُ وَأَحْيَا
Bismika Allahumma amutu wa ahya.
Meaning: In Your name, O Allah, I die and I live.
Source: Sahih al-Bukhari #6314Sleep is referred to as a 'minor death' in Islamic tradition. By reciting this dua, the believer acknowledges that sleep and wakefulness are in Allah's hands alone. It is a profound act of trust and submission, recognizing that every night we 'die' in sleep and every morning Allah gives us life anew.
بِاسْمِكَ اللَّهُمَّ أَمُوتُ وَأَحْيَا
When the Prophet (peace be upon him) went to bed at night, he would put his hand under his cheek and then say: 'Bismika Allahumma amutu wa ahya,' and when he woke up he would say: 'Al-hamdu lillahil-ladhi ahyana ba'da ma amatana wa ilayhin-nushur.'