I experimented with this for about 6 months. This is of course very subjective but I found that I could sleep less hours and feel as rested. More important was how productive I was for the first 4 hours after sleep, getting to feel that alertness you feel every morning MULTIPLE times per day. To me this seems like the ultimate tool for productivity, for 6 weeks while I was studying hard in school I managed to get 8-11 hours of study per day consistently which is just entirely impossible for me on a normal sleeping schedule. Too bad people make noise during the day-time.