National Geographic : 2018 Aug
Sleep is seen as inter- rupting life, but the real scourge is chronic sleeplessness. In Japan about 40 percent of the population sleeps less than six hours a night. Public dozing, as at this all-night diner in Tokyo, is socially accepted. PREVIOUS PHOTO Wile, the seven- year-old son of pho- tographer Magnus Wennman, watches cartoons on his iPad— a modern bedtime ritual for some. The stimulation may drive off sleep, but so does the backlit screen: Light at night inhibits the production of mela- tonin, the hormone that helps regulate our daily biological rhythms. Americans sleep less than seven hours a night, about two hours less than a century ago. In our restless floodlit society, we often think of sleep as an adversary.