How many hours did our prophet Muhammad sallallahu alaihi wasallam used to sleep?
Waalakum as Salam wa rahmatullahi wa barakatuhu,
The Prophet (sallAllahu ‘alayhi wa sallam) would sleep in the second third of the night. He would also take a short nap after the time of Fajr set in, until the Fajr prayer, and he would sleep for a little while in the afternoon.
All these would total to around 7-8 hours. Bear in mind that Prophet’s (sallAllahu ‘alayhi wa sallam) blessed eyes would sleep, but his noble heart would not sleep.
And Allaah Ta’aala knows best
Ismail Moosa (Mufti)
وكان نومه أعدلَ النوم، وهو أنفع ما يكون من النوم، والأطباء يقولون: هو ثلث الليل والنهار، ثمان ساعات. (زاد المعاد في هدي خير العباد – 1/ 159)
This answer was collected from Fatwaa.com which is an excellent Q&A site managed by Mufti Ismail Moosa from South Africa. .