Sleeping is similar to death. That is why sleeping has been linked to death, and waking with life. When preparing to sleep we should fear that may be our eyes close and do not open again. This has happened many times ; hence we should ask Allah (The Exalted) for forgiveness of our sins as it is not good to do so without.
The pious would sleep little as the time spent in sleep is of no use. Only if we are successful and able to understand to reality of our life. For instance if someone has a life of 60 years and sleeps for 8 hours a day then we would have spend 20 years in sleep, that’s 1/3 of the life spent in sleeping. In these 20 years we did not achieve anything, however, if we spend our sleeping in the way of the Prophet (may Allah bless him and grant him peace) then Inshallah we will gain some benefit as this will become worship.