Analysis of daylight saving time

Daylight saving time (DST) is the practice of advancing clocks during warmer months so that darkness falls later each day according to the clock.

Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and therefore is good for physical and psychological health, reduces traffic accidents, reduces crime or is good for business.^{[citation needed]}

Opponents argue that DST disrupts human circadian rhythms (negatively impacting human health in the process),^[1][2] that it increases fatal traffic collisions,^[3] that the actual energy savings are inconclusive,^[4] and that DST increases health risks such as heart attack.^[4] Farmers have tended to oppose DST.^[5][6]

Having a common agreement about the day's layout or schedule has so many advantages that a standard schedule over whole countries or large areas has generally been chosen over efforts in which some people get up earlier and others do not.^[7] The advantages of coordination are so great that many people ignore whether DST is in effect by altering their work schedules to coordinate with television broadcasts or daylight.^[8] DST is commonly not observed during most of winter, because the days are shorter then; workers may have no sunlit leisure time, and students may need to leave for school in the dark.^[9] Since DST is applied to many varying communities, its effects may be very different depending on their culture, light levels, geography, and climate. Because of this variation, it is hard to make generalized conclusions about the effects of the practice. The costs and benefits may differ between places. Some areas may adopt DST simply as a matter of coordination with other areas rather than for any other benefits.