Monday, March 12, 2007
Spring forward, falling back: Bad for your health?
When I was a kid, daylight-saving time was a glorious time of the year. It meant two things: warmer weather and more hours of schoolyard antics for me and my ball-playing buddies. I used to look forward to it. It used to make me as happy as a vacation day from school.
Now as an adult, daylight-saving time means one thing: one less hour of precious sleep. As I groggily dragged myself out of bed, I just had to wonder: Can one less hour in bed affect my health?
First, I had to find out a bit more about daylight-saving time itself. After all, it seems like a misnomer. You can't really save daylight. We can change, wind or even break the clocks as much as we want, but I'll still get about 12 hours of sunlight in New York today. One of the main purposes for DST is energy conservation. The idea is that daylight should coincide with peak activity times. So, we spring forward so that we don't sleep through that early morning daylight. Also, it gives us more natural light in the evenings. With the clocks moving forward, we use less energy, through acts such as lighting our houses later at night.
How and when did DST all begin? Well, with politicians, of course. Germany was the first nation to enact it in 1915. These days approximately 70 countries worldwide observe DST. Almost all of the United States practices DST except for parts of Arizona and Indiana. In 1918, the U.S. Congress passed the first DST law, but repealed it a year later. In 1966, the Congress enacted the Uniform Time Act which established a uniform DST throughout most of the country. This year, with the Energy Policy Act of 2005 going into effect, DST started three weeks early.
Does all this temporal law-making affect our health? The answer is a definitive maybe. On the bright side, it could mean good news for your oral health. The additional amount of daylight could stimulate your body’s vitamin D production and strengthen your teeth and bones according a study in the Journal of Periodontology. A small 2006 Finnish study found that people who regularly sleep less than eight hours or who are more active at night have a much harder time adjusting to the DST change.
There has also been a good deal of research looking into DST and traffic accidents. The reviews are mixed. In the long-term, DST has been shown to save lives through reduced automobile crashes. The researchers say accidents decrease because more people are traveling during daylight hours and fewer are driving during the accident-prone nighttime. But in the short-term, a Canadian researcher found that springing forward is associated with a slight increase in the number of accidental car deaths. Stanley Coren of the University of British Columbia found a 6.5 percent to 8 percent rise on the Monday immediately following the time change. That's compared with no increases associated with the falling backward shift.
What do you think about daylight-saving time? Do you think it has any impact on our health? Is the practice useful to you? Do you think energy conservation is a direct result? Are there any harmful effects?
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