It depends on what I am eating. When I was trying to shrink what was in my gallbladder (RIP) I had a diet that was so pristine and nutrient laden that I was sleeping about thee hours a day and working.
Now I sleep a full six or seven. I still eat fairly good, but not that healthy. That was expensive as heck too. The spirulina alone was over 200 a month.
I sleep whenever I feel sleepy. I am old and rich and I don't need to keep track of hours. I hit the sack when I feel like hitting the sack and I get up when I need to pee.
You have interrupted sleep when you suffer pain, as you know. On bad days I can still be awake when the sun comes up, on the better days often with the help of medication, approximately 6 - 8 hours (but always broken sleep). I did go to a sleep clinic once, they wired me up like terminator, electrodes on my head, body and legs. I had to press a button every time I wanted to go to the loo, and wait for a nurse to come and unplug me. I got 30 minutes sleep in total. Still, the only consolation is I'm not the only one awake at silly o'clock, there are other people suffering in silence during those hours too.