اللَّهُمَّ أَسْلَمْتُ نَفْسِي إِلَيْكَ وَوَجَّهْتُ وَجْهِي إِلَيْكَ وَفَوَّضْتُ أَمْرِي إِلَيْكَ وَأَلْجَأْتُ ظَهْرِي إِلَيْكَ رَغْبَةً وَرَهْبَةً إِلَيْكَ لَا مَلْجَأَ وَلَا مَنْجَا مِنْكَ إِلَّا إِلَيْكَ آمَنْتُ بِكِتَابِكَ الَّذِي أَنْزَلْتَ وَنَبِيِّكَ الَّذِي أَرْسَلْتَ
"I submit my life to you, I turn towards You and leave my work unto you, I lean on you, desire your boons and fear you as there is no other salvation besides you. I believe in the Kitab (Book) you have revealed and in the Rasul(Prophet) you have sent.
Prophet Mohammad (S.A.W.) showed (taught a Sahabi) this dua and said: "If after reading it you die in the night, then it is as if you have died on 'Natural Deen' and if you awake in the morning alive then you will have good fortune".
(Mishkat)
Anas (R.A.) narrates that Prophet Mohammad (S.A.W.) said that if a person retires to bed on the side and recites Surah Fatiha and Surah Ikhlaas (Qul huwa- Allah Ahad) he is immune from everything besides death.
(Hisnul Hasan from Albazr)
Sahabi (R.A.) requested Prophet Mohammad (S.A.W.) that Prophet Mohammad (S.A.W.) teach him something to recite at the time of retiring to bed. Prophet Mohammad (S.A.W.) said: "Recite Qul Ya Ayuhal Kafiroon, for in it (there is an announcement) to refrain from shirk.
(Mishkat from Tirmidhi)
In some ahadith, it is stated that one should sleep after reciting (i.e. not to talk after reciting it).
(Hisnul Hasin from Albazr)
Ayesha (R.A.) narrates that when Prophet Mohammad (S.A.W.) used to go to the room for sleep, he used to recite Suras Ikhlaas, Falaq, Nass and blow onto his hand (palms) in such a manner that the saliva would drop on them and then he would rub them over his body three times starting from the front of the face.
(Bukhari, Muslim)
Besides this, he would recite
33 times سُبْحَانَ اللَّهِ
33 times الْحَمْدُ لِلَّهِ
34 times اللَّهُ أَكْبَرُ
He also used to recite Ayatul Qursi as Allah has stipulated that the reciter will be protected throughout the night by the angels and the Satan will not come near.
(Bukhari)
أَسْتَغْفِرُ اللَّهَ الَّذِي لَا إِلَهَ إِلَّا هُوَ الْحَيَّ الْقَيُّومَ وَأَتُوبِ إِلَيْهِ
Its virtues are that all the reciter's sins will be forgiven even if it be equal to the extent of the foam in the ocean.
(Tirmidhi)
Recite Bismillah while closing doors, covering utensils, and putting off the light (candles, etc.)
(Mishkat)
Prophet Mohammad (S.A.W.) said that when a person enters his bed (to sleep), an angel and a Shaitaan surround him. The Shaitaan whispers 'your awakening will end in evil' and the angel says' end in good". One sleeps after engaging in dhikr, the angels will protect him throughout the night. In order to gain the protection of the angels, it is wise to engage in Dhikr and then sleep.
(Hisnul Hasin)