We gave it an A-
The optimal amount of sleep per day — 9 to 10 hours — might strike those living the American work-hard, play-hard ethic like a prescription from dreamland. Yet Stanley Coren, a professor of psychology at the University of British Columbia, convincingly argues in Sleep Thieves: An Eye-opening Exploration Into the Science and Mysteries of Sleep that doing so will make us smarter, more productive, and happier. Mixing science with anecdote, he explains how avoiding ”sleep debts” not only staves off depression and concentration loss, but can also prevent you from becoming a grim statistic: There are nearly 25,000 deaths per year caused by ”sleep-related errors and accidents.” What of those brilliant people in history — Winston Churchill, Thomas Edison — who slept only a few hours per night? All big nappers.