Shift work has previously been linked to an increased risk of developing MS, presumably due to the resulting sleep deprivation and circadian desynchrony. The current study compared sleeping 7–9 hours/night during adolescence, with less than 7 hours/night and found a 40% increase in risk for developing MS in the short-sleep cohort. The authors conclude that “insufficient sleep and low sleep quality during adolescence seem to increase the risk of subsequently developing MS.”