I have trouble getting to sleep, hubby closes his eyes and snoring starts. I usually lie in bed for a couple of hours (listening to the snoring and playing RF) until my eyelids droop and my eyes can no longer focus. Switch off the light and im gone. Five and a half hours later i wake feeling refreshed and ready for coffee.
I'm impressed that you feel refreshed after 5.5 hours! I need 9 to really be comfortable(but can function with 7-8). I had a roommate that needed 12 hours... She really wasn't lazy, she just seemed to mentally fall apart without it(there may have been other health issues involved).