It's time again to "spring forward" and get another hour of sunlight in the evening. Most people, however, don't know about the health and public safety effects of Daylight Saving Time (DST).
You don't have to worry about it if you live in Arizona or Hawaii. These two states do not observe DST and neither do the three U.S. territories -- American Samoa, Puerto Rico and the U.S. Virgin Islands. They all get lots of sunlight anyway.
By the way, drop the final "s" on "saving." The official phrase is "daylight saving time," which is not pluralized. Interestingly, a whole lot more folks Google the wrong phrase compared to the correct one, according to U.S. News & World Report.
There are some interesting facts about daylight saving time:
THERE MUST BE A LAW
Although most people believe there is a federal rule mandating that states or territories observe daylight saving time, there is none.
There was a 1918 law which legislated for the observance of DST nationwide, but that section of the law was repealed the next year. After that, DST became an issue left up to local jurisdictions. It was actually the Germans and their WWI allies that began using it first. Daylight saving time was observed nationally again during World War II, but after the war's end was not uniformly practiced.
It wasn't until 1966 that Congress passed the Uniform Time Act, which standardized the start and end dates for DST, yet permitted individual states to stay on standard time if their legislatures allowed it, according to National Geographic News.
Daylight Saving Time seems to both end and save lives.
BAD FOR THE HEART
There is a spike in heart attacks when daylight saving time comes. In fact, springing forward seems to both end and save lives. At the Karolinska Institute in Stockholm, researchers looked at myocardial infarction rates in Sweden since 1987. They found that the number of heart attacks rose some 5 percent during the first week of DST -- summer time in Europe. Last October, the New England Journal of Medicine suggested that this increase may result from the disruption of sleep patterns and biological rhythms.
GOOD FOR TRAFFIC ACCIDENTS
At the same time, the clock shift may help prevent traffic accidents because more people are driving home in sunlight. RAND Corporation economists analyzed 28 years of U.S. automobile crash data and suggest that the 1986 DST extension -- moving the start of daylight time from the last Sunday in April to the first -- produced an 8 to 11 percent drop in crashes involving pedestrians and a 6 to 10 percent dip in crashes for vehicular occupants, as reported by Scientific American.
DOES IT SAVE ENERGY?
Starting today, around one quarter of the world's population gains an extra hour of sunlight in the evening having set their clocks ahead for daylight saving time. Some believe the time shift produces electricity conservation, energy savings due to the extra sunlight. But some recent research casts doubt about energy savings -- with some studies finding that DST ultimately leads to greater power use. For example, the use of more air conditioning could cause more energy drainage rather than savings.
However, last fall the U.S. Department of Energy analysts reported on their study of what effect DST might have on national energy consumption. They looked at 67 electric utilities across the country. In their report to Congress (October 2008), they found that the four-week extension of daylight time saved around 0.5 percent of the nation's electricity per day, or 1.3 trillion watt-hours in total, which could power 100,000 households for a year.
So far, it's a toss up whether or not DST saves or spends energy.
By Sharon McEachern
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