You'll recognize the beginning of Daylight Saving Time (DST) by the longer, lighter days of early spring and the return to Standard Time by the darker afternoons and earlier sunsets of late autumn when we "fall back," sneaking in some extra daylight or an extra hour of sleep by turning back our clocks an hour. Some researchers, however, suggest that these time changes may be bad for our bodies.
The science of DST, as you will find out, is not about the diurnal cycles of day and night, but about energy savings.
Daylight Saving Time for Kids
- What is Daylight Saving Time, anyway? - nationalgeographic.com
- How Time Works - howstuffworks.com
- Daylight Saving Time - webexhibits.org
Daylight Savings To Save Energy
Daylight savings time is set by the government, not by health experts. The practice of shifting clocks bi-annually began in the U.S. during World Wars I and II to save energy and resources for the war.
In 2007, the U.S. Congress adjusted daylight savings to begin three weeks earlier and end one week later in to further save on energy and associated costs, via the Energy Policy Act of 2005.
I-Am-Bored features a video explaining The Cost of Daylight Saving Time (video), including the history and reasons behind DST, and some interesting facts, i.e., Arizona and Hawaii ignore the time change. They've got plenty of sunlight year round.
DST begins March 11, 2012 at 2 a.m. As of October 30 or November 4, 2012 (U.S.), we'll be back on Standard Time (ST).
In the U.K., Daylight Saving Time is also called British Summer Time (BST).
Daylight Savings Health Effects
"During the winter," says Till Roenneberg of Germany, lead researcher for a study of the effects of time shifts, "there is a beautiful tracking of dawn in human sleep behavior, which is completely and immediately interrupted when daylight saving time is introduced in March."
In 2008, researchers in Sweden reported that the number of heart attacks jump during the period immediately following time changes in the spring and reduce slightly when the time is shifted back in the fall.
"These transitions," say health and welfare researchers Imre Janszky and Rickard Ljung of Sweden, "can disrupt chronobiologic rhythms and influence the duration and quality of sleep, and the effect lasts for several days after the shifts."
When to Change the Clock
Technically, DST begins on March 11, 2012 at 2 a.m. and ends at 2 a.m. on either October 30 or November 4 (U.S.), but many people set the clock back one hour before they go to bed. In either case, you'll want to check whether your clocks adjust themselves, so you don't fall back double.
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Sources:
Curry, Colleen. "Daylight Savings 2011: Ends Nov. 6, and It's Good for Your Body." abcnews.go.com, 21 Oct 2011.
Janszky I, Ljung R. "Shifts to and from Daylight Saving Time and Incidence of Myocardial Infarction." New England Journal of Medicine, 30 October 2008, 359;18:1966-68.
Sara McGrath - Sara is a veteran homeschool mom of three, Usborne consultant, and the author of Unschooling: A Lifestyle of Learning.
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