Matthew J. Wolf-Meyer blames capitalism in general and American capitalism in particular for transforming once perfectly ordinary behavior into conduct worthy of medication. “The consolidated model of sleep is predicated upon the solidification of other institutional times in American society, foremost among them work time,” he writes. It is “largely the by-product of the industrial workday, which began as a dawn-to-dusk twelve-to-sixteen hour stretch and shrank to an eight-hour period only at the turn of the twentieth century.” So many people have trouble getting enough sleep between eleven at night and seven in the morning because sleeping from eleven to seven isn’t what people were designed to do.