Humans are considered monophasic sleepers — meaning that they sleep for a single long stretch (typically at night). This makes sense because the absence of daylight during the evening makes it impractical to work or do outdoor activities. Or at least it did before the evolution of artificial lighting. With the rise of the “night shift” and extended work hours, many people are adopting what’s known as a polyphasic sleep pattern, aka napping, which involves sleeping when schedules allow. The real question is: is napping good for you? Members of the World Sleep Congress say most likely; however, some research suggests that excessive amounts of sleep can do more harm than good.