03/09/2012 08:23 am ET Updated Mar 09, 2012

8 Hours Of Sleep vs. 2-Part Sleep: Harvard Professor Discusses The History Of A Good Night's Rest

As part of National Sleep Awareness Week, the National Sleep Foundation's annual campaign to remind people about the importance and value of sleep, The Huffington Post and The Forum at Harvard School of Public Health collaborated on a live webcast event titled "Fighting the Clock: How America's Sleep Deficit is Damaging Longterm Health."

In this highlight from the event, an online audience member sends in a question about the history of the eight-hour night's sleep. Charles Czeisler, M.D. Ph.D., chief of the division of sleep medicine at Brigham and Women's Hospital in Boston, and professor and director of the division of sleep medicine at Harvard Medical School, explains that many people divided the night into two separate periods of sleep in the past. Although today we have mostly evolved away from that model, it may provide some explanation for why some people often wake up in the middle of the night, he explains. "The current concern that you have to go to the doctor and get a pill if you wake up during the night is probably misguided," he says.

Do you wake up in the middle of the night? How do you fall back to sleep? Tell us in the comments.

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