In much of the United States, there is a twice-yearly shift in timekeeping between standard time and daylight saving time, or DST, which delays both sunrise and sunset to make mornings darker and evenings brighter. Recently, scientists, policy experts, lawmakers and citizens have debated abandoning the twice-a-year switch and adopting either year-round standard time or DST. A team of researchers at the University of Washington — led by postdoctoral researcher Calum Cunningham and Laura Prugh, an associate professor of quantitative wildlife sciences — have found that one of those options would sharply reduce a hazard common to much of the country: deer-vehicle collisions.