On a purely selfish level, I enjoy the switch from Daylight Saving Time to Standard Time. Anything that gives me an extra hour of sleep is a cause for celebration for my sleep-deprived brain, and I imagine many college students feel the same (especially since midterm season is just ending and we can finally relax from studying a bit).
Thinking too hard about the concept of Daylight Saving Time, however, makes one wonder why it was a good idea. Yes, the original goal was to give an extra hour of sunlight as the fall and winter make for earlier evenings and therefore save electricity. However, the concept does create confusion for those who don’t pay attention to the dates of the switch-overs or forget the concept of “Spring forward, fall back.”
If you find it confusing now, you should know that there are certain areas that don’t observe Daylight Saving Time at all. Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and most of Arizona (with the exception of the Navajo Reservation) do not switch their clocks. There is no federal law requiring that states observe Daylight Saving Time, only that if they do, it must begin at 2 a.m. on the second Sunday in March and end at 2 a.m. on the first Sunday of November.
Even these regulations are subject to change; this range of Daylight Saving Time is actually from the Energy Policy Act of 2005. Until the Uniform Time Act of 1966, when Daylight Saving Time was set from the last Sunday in April to the last Sunday of October, every locality was free to choose when to change their clocks for Daylight Saving Time, which caused a great deal of confusion for the broadcasting and travel industries.
The law was amended in 1986 to change the spring-forward date to the first Sunday in April, extending Daylight Saving Time by nearly a month. At this time, the fall-backward date was in the last Sunday of October and remained with these dates until 2005, when the date was changed to the first Sunday of November.
But why does all of this confusion need to exist at all? The most basic reason is that the Earth’s axis is tilted relative to its orbit around the sun. As the planet revolves around the sun, this tilt means that at different points of its orbit, different parts of the earth are closer to the star, which is why we have seasons and why winter in the northern hemisphere occurs at the same time as summer in the southern hemisphere (and vice versa).
When our hemisphere is tilted away from the sun, it also means that we spend a greater amount of time in darkness. People have known this for thousands of years, and different cities set their clocks differently depending on their own sunlight, but it wasn’t until common use of public transportation that knowing the time became a requirement.
The first proposal for setting the clock forward for spring and summer was from Benjamin Franklin in 1784, but the idea didn’t catch on until a proposal from an Englishman named William Willett in 1907.
Willett’s idea left something to be desired. He wanted to move the clocks 80 minutes ahead during the summer months — in four, 20-minute increments. This plan is more precise compared to the one-hour jump we do today with regard to the Earth’s tilted axis, as the length of daylight increases gradually (not all at once) during spring.
However, who here would be able to keep track of how often to turn the clocks ahead 20 minutes four times per year, as well as back 20 minutes another four times per year? Sometimes, scientific precision has to take a backseat to practicality.
The issue of scientific precision versus practical usefulness comes up again in one of the major claims of Daylight Saving Time: that it reduces electricity use. The precise, scientific answer appears to be that yes, it does. Is this reduced use enough for the average person to notice? Not really.
The first national study was commissioned by the United States Department of Transportation in the 1970s and found that, nationally speaking, electricity usage decreased by 1 percent each day when using Daylight Saving Time. A similar study from 2008 from the United States Department of Energy found that extending Daylight Saving Time by one month reduced national electricity usage by 0.03 percent.
Not per person — nationally. Of course, every little bit of electricity saved is helpful. Just don’t expect to see that difference reflected in your utility bill.
Have a science question? E-mail AMY STEWART at firstname.lastname@example.org and she’ll find an expert to ask.