During what hours do you sleep?
This varies. Often after midnight. Usually (on the weekdays) until 05:30.
Do you wake up often while sleeping?
Usually not. Mostly if I fall asleep, I sleep until I wake up. Either on my own, or by the alarm clock on my phone.
That is not much sleep at all. Have you considered getting 7-8 hours? I don't think anything more than that is needed, but I used to feel terrible when I only slept 4-6 hours each day. I was someone who always was up past midnight, often late into the morning. Not anymore. Always asleep before midnight now, usually closer to 10 or 11.
I know that the normal sleep would be 7-8 hours, but often I simply cannot sleep. I do not know why. And somehow I often think more in the evening/night than in the other parts of the day.