From the Sunan of going to sleep, is:
1. Say the supplication for the going to sleep.
Allahumma Bismika Ahyaa Wa-Amuutu
O Allah, In your name, I live and I die.
2. Recite the Mu'awwidhat and wipe the body:
The Prophet (PBUH) cupped his hands together and Yanfuth in them and then read:
... and then he would wipe whatever he was able to of his body with his hands, beginning with the head and face and then the remaining part of the body.
He would do this three times.
3. The last two ayaat of Soorah Al-Baqarah
"The messenger believe in what has been sent down to him..."
(Al-Baqarah, 2:285- 6)
This is taken from the hadeeth: Whoever reads them (i.e the last two Verses) at night they will be Kafataa for him.
Imam An-Nawawee said:
The scholars have differed as to the meaning of Kafataa. It is said that it means they are sufficient for him regarding the Night Prayer and it was also said it means they are sufficient in protection from every evil, misfortune and harm. I say both of these meaning are acceptable...
4. Recite Aayah Al-Kursee:
"Allah, none has the right to be worshipped, but He, the Ever-Living..."
From the benifits of reciting this is that:
For whoever reads it, there would remain a protection over him from Allah and Syaytaan would not come close to him.
From the etiquettes of going to sleep, we should:
1. Be in state of purity, from the Hadeeth:
If you come to your bed (i.e. go to sleep) then perform Wudoo'.
2. Sleep on our right side:
....then lie down on your right side.
3. Place the right hand under the right cheek:
When he (PBUH) went to sleep, he placed his right hand under his right cheek...
4. Dust the bed:
When one of you goes to bed, let him dust the bed because he does not know what comes into it before or after him.
5. Recite Soorah Al-Kaafirun:
"Say: 'O you disbelievers...' "
From its benifits:
It frees the person from Shirik.