[srik]

I can't find my paper in time, but I did some study on this and apparently many (long) studies have shown that the ideal sleep time is 6-6:30 hours a day. Any variation either way of that duration affected 3+years longevity if I remember correctly.

(This is not a scientific study ,so take it with a grain of salt - http://www.time.com/time/health/article/0,8599,1812420,00.ht... )