Age, gender and nationality affect how much sleep you get, study finds

What constitutes a "normal" night's sleep?

That all depends, says Danny Forger, a biological mathematician at the University of Michigan and an expert in circadian clocks.

"People set guidelines all the time -- you need eight hours, you need seven hours -- but we've found that 'normal' sleep varies...

via L.A. Times - Science http://ift.tt/1Wdi9ZO