Our floodlit society has made sleep deprivation a lifestyle. But we know more than ever about how we rest—and how it keeps us healthy. Joe Diemand, 76, has spent the past 20 years as a truck ...

His work using all-night electroencephalogram (EEG) recordings allowed Kleitman and his team to chart ... In the past century, scientists have recognized several sleep disorders, such as narcolepsy, ...