Daylight saving time is the practice of moving clocks forward by one hour during summer months so that daylight lasts longer into evening. Most of North America and Europe follows the custom, while the majority of countries elsewhere do not. According to a growing body of scientific research, when clocks in almost all of the United States spring forward by an hour on Sunday, it will likely prompt an increase in heart attacks and strokes, cause more car accidents and reduce worker productivity, according to studies. It will also fail to cut the nation’s energy bill, contrary to what the experts once believed. Disruptions, even minor ones, to human beings’ sleep patterns can have outsized effects.