Yes you absolutely can, ...but I think it heavily depends on how much you tax yourself during your waking hours and whether what you do in your waking hours is more taxing mentally, or physically. or emotionally.
When I worked on set, I would do 15 - 16 hr days for days at a time and get by on 6 hours sleep a night (if I was lucky), but after a few days it always caught up with me, and I would sometimes be comatose for 2 days, only to turn around and do it again the next week. By the time the project was over, I'd end up comatose for a week.
For the past few years, I've regularly been operating on 6 hrs sleep, most frequently between 5am - 11am, or 6am - noon, and it's worked fine for me. As long as I cut out artificial stimulants like caffeine, I'm good to go. Sometimes I even function well on only 5 hrs of sleep. Whatever my body tells me I need, that's what I take. I tossed the alarm clock in 2002.
I don't think anybody who lifts should try 6 hrs though, especially NOT if your body is in a growth phase,
...I'd say take as many hours a night as your body tells you to take.
