Abu Lahya argues sleeping more than six hours wastes time. He recommends sleeping 9 PM to 3 AM, praying qiyamul-layl, then napping briefly, claiming this yields ten productive waking hours and follows the Prophet Muhammad's example.
Chapters
If you sleep more than 6 hours, you're wasting your life.
4 to 6 hours of sleep, couple that with the qaylula nap, you're good. The sleeping time is important on your recovery. We see that Prophet (pbuh) was sleeping after Isha. The scientists who made research and said that the sleep you would get on the early part of the night is better for your recovery than the sleep you get later during the night. Which means before Isha, usually Isha is around 7, 8, or 9 PM. Let's say you sleep 9 PM to 3 AM, that's your 6 hours. You get a lot of productive sleep and then you pray qiyamul-layl, you start your day, have a little qaylula. Your day is so much longer. Imagine the barakah you can have. Have if you wake up at 3, 4 AM and you feel fresh. Imagine how much you can achieve until Doha. That's 10 hours. You can have 10 hours of productivity. Imagine the amazing day you had, and then you go to sleep, wake up again the next day. So much productivity. It is beautiful.