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

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

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%)."