Throughout history, people have timed their bathing for a number of important purposes. Some cultures have showered in the morning to purify the spirit before prayer, while others preferred the evening bath as an opportunity to socialize and clean their grimy bodies before bed. Shahab Haghayegh just wanted to get a better night’s sleep. “I tried various methods including melatonin pills to move my bedtime back,” he says. “Nothing worked.” What finally did the trick? Switching his shower from