Permanent standard time could cut obesity and strokes, Stanford study

Stanford Medicine researchers say abandoning the twice yearly clock changes and adopting permanent standard time across the United States could yield measurable public health benefits, according to a study published Monday in Proceedings of the National Academy of Sciences. Using county level modeling, the team estimates that staying on standard time year round could prevent roughly 300,000 strokes and reduce the number of Americans living with obesity by about 2.6 million annually, compared with the current practice of springing forward and falling back.

The research, led by bioengineering graduate student Lara Weed with senior author Jamie Zeitzer, modeled how three time policies permanent standard time, permanent daylight saving time, and the current biannual shifting affect light exposure, circadian rhythms and health outcomes. The authors combined simulated light exposure based on local sunrise and sunset times with a mathematical model of the circadian clock and linked those results to county prevalence data from the Centers for Disease Control and Prevention for conditions such as obesity and stroke.

Changing clocks twice a year causes abrupt circadian disruption, the...