Proper Sleep

Sleep Timing

http://www.doctoroz.com/blog/kulreet-chaudhary-md/sleep-and-longevity

"Timing your sleep is like timing an investment in the stock market – it doesn’t matter how much you invest, it matters when you invest."

Sleep Duration

of 21,000 case studies with twins - "if people slept less than 7 hours a night or more than 8 hours a night, they had an increased risk of death. For short sleep women, that increase was 21% (men: 26%) and for long sleeping women, the increase was 17% (men: 24%)."

http://longevity.about.com/od/sleephealthandaging/a/sleep_duration.htm

But also, there are some high energy people for whom 4 hours of sleep is fine.

http://books.google.com/books?id=s827FuPms14C&pg=PA71&lpg=PA71&dq=going+to+bed+at+a+regular+time+and+longevity&source=bl&ots=1wjExLYH8A&sig=v2yBJkMHQBQJayRP7Ia3bN0fHEQ&hl=en&sa=X&ei=ohKFUIWbFqTR2QW-_IHoDA&ved=0CCgQ6AEwAQ#v=onepage&q=going%20to%20bed%20at%20a%20regular%20time%20and%20longevity&f=false