Daylight Saving Time: Health, Car Accidents and Energy Usage

“Spring forward, fall back.” Like clockwork, we follow this humble command twice a year. But what is it doing to our health and wellbeing?
(David Trilling)
(David Trilling)

By David Trilling

The idea behind daylight saving time (DST) — when we move our clocks forward by one hour for the warmer months, giving us an extra hour on an autumn Sunday and losing us one in spring — is to make better use of daylight and conserve energy. A later sunset during the long summer days means less need for indoor lighting in the evening. The idea has been around for centuries. Some credit a 1784 essay by Benjamin Franklin.

Germany was the first country to adopt DST, in 1916, to save energy during World War I. Other countries quickly followed. In the 1970s, during the Arab oil embargo, the U.S. Congress approved an emergency yearlong DST. In 2005, the Energy Policy Act extended the observance of DST in the United States by four weeks. Americans (except in Arizona and Hawaii, which do not use DST) now set their clocks forward on the second Sunday in March and back on the first Sunday in November.

Yet academic research shows largely negative impacts on health, which have stoked controversy in recent decades and led some to question if this century-old tradition still merits support. Indeed, some countries, like Argentina and Russia, have dropped DST altogether.

The spring is most dangerous: In the first few days after we lose an hour of sleep, researchers have shown increases in car accidents and heart attacks. Those phenomena may decrease for a few days after the fall switch, when we are given that extra hour of sleep. Another study reports a mild health boost in the fall, though a 2016 study in Epidemiology found increased depressive episodes in the autumn, when the change means we are suddenly leaving work in the dark.

People with small children report higher levels of unhappiness during the spring transition, when they lose an hour of sleep. Without DST, though, parents worry about children leaving for school on dark winter mornings. Crime drops after the spring change.

As for energy consumption, in a 2008 study carried out shortly after the last federal change to the daylight saving schedule, the U.S. Department of Energy found annual energy usage fell about 0.03 percent. That may not sound like much, but it is enough to power 100,000 homes for a year. Other research found savings higher in regions far from the equator, where the length of the day varies considerably throughout the year. Yet usage near the equator, where the amount of daylight varies little, actually increased after the clocks were switched, they found.

Fun Facts

tip sheet from the Department of Energy details more history behind DST and suggests that Benjamin Franklin was joking when he proposed changing our clocks.

The website lists countries and the dates they change their clocks. Many — including China and Russia — do not change at all.

Source: Journalist’s Resource