“Most of us now sleep less than people did a century ago, or even 50 years ago. The National Sleep Foundation’s 2005 poll showed adult Americans averaging 6.8 hours of sleep on weeknights — more than an hour less than they need. Not only how much sleep, but when people sleep has changed. In the United States, six to eight million shift workers toil regularly at night, disrupting sleep patterns in ways that are not necessarily amenable to adaptation.” The question is: What are we losing by sleeping less?