Sleeping is a way for our brains to flash out all the toxins that accumulated in the brain throughout the day. A kind of human garbage collector.
I don't limit my sleep and I try to sleep as much as my body needs.
I try to go to bed and wake up at the same time each day to maintain the Circadian rhythm. I try to go to sleep at 22:00 and waking up at 6:00 every morning, making sure I go through my night/morning routines fully. I never use my phone in bed and always charge it away from the bed. And I sleep without a pillow.