It seems like a simple gesture: Spring forward, Fall back. Yet does anyone know what we’re doing asks Michael Downing. (1)
Daylight Saving Time (DST) is perhaps the most persistent political controversy in American history. Although DST has been around since 1918, no one can say for sure why we are required by law to change our clocks twice a year. The goal of DST—to use daylight to its maximum advantage—is generally recognized to be of universal benefit. But few people understand how surprisingly controversial this deceptively simple idea has been.
Proponents have proclaimed DST’s benefits including saving energy, reducing automobile accidents, providing more daylight for outdoor activities, cutting crime, and many others. But DST also has had many detractors—from farmers to parents of schoolchildren—who have waged contentious battles against it. (2)
Today DST is observed in over seventy countries worldwide. But DST is also heavily criticized for the inconveniences it creates on the days when the switch between DST and Standard Time occurs. (3)
The latest iteration we experienced with DST happened on March 11, 2007. Daylight time now begins on the second Sunday in March and ends on the first Sunday in November. This is a significant change from the former (1986) rule of first Sunday in April to last Sunday in October. (4)
Early studies supporting DST often relied on simulation models and extrapolation rather than empirical evidence. In recent times a number of new studies question the validity of the earlier work.
Scientists at the University of California Energy Institute reported that extending DST to March 2007 failed to conserve energy in Australia. (3) In a similar vein, another report concluded that the extension of DST to March 2007 had little or no effect on energy consumption in California. (5)
A 2008 study in Indiana found that daylight time caused a 1 percent overall increase in residential electricity use, though the effect varied from month to month. The greatest increase occurred in late summer and early fall, when electricity use rose by 2 percent to 4 percent. Researchers studied 7 million electric bills over three years in Indiana where for decades 77 counties chose to skip the spring ahead and fall behind process. Against the intuition and contrary to the entire point of government policy, the study found that daylight saving time resulted in an $8.6 million increase in spending on residential electricity. (6) So at the very lest, we should abandon the notion that we are saving energy while enjoying an extra hour of sunlight on hot summer evenings.
When people living in many parts of the world move their clocks forward one hour in the spring in observance of daylight saving time, their bodies’ internal daily rhythms don’t adjust with them, reports Thomas Kantermann and colleagues. They examined the sleep patterns of 55,000 people in Central Europe. The timing of sleep on free days followed the seasonal progression of dawn under standard time, but not under DST. Their findings suggest that this regular time change—practiced by a quarter of the human population—represents a significant seasonal disruption, raising the possibility that DST may have unintended effects on other aspects of human physiology. (7)
In another study, scientists tracked large groups of people for eight weeks at a time as they made the transitions to daylight time in spring and to standard time in autumn. They found that in spring people’s peak activity levels were more in tune with their body clock than with actual clock. Studies suggest that this disconnect between body time and clock time can result in restlessness, sleep disruption and shorter sleep duration. (8) Other studies have suggested links between time change and increases in heart attacks, suicides, and accidents, though scientists say more study is needed. The bottom line is that DST is associated with sleep disruptions and possibly more serious consequences. (9)
According to Stanley Coren, a sleep expert at the University of British Columbia, the number of traffic accidents and fatal industrial mishaps increase on the Black Monday following the Spring switch to DST. Apparently, for some people the loss of one hour’s sleep is enough to dampen their reflexes. (4)
Some final observations
Amtrak’s record of being on-time leaves something to be desired. Yet here’s a twist. A standard rule is that to keep their published timetables, trains cannot leave a station before the scheduled time. So, when the clocks fall back one hour in November, all Amtrak trains in the US that are running on time stop at 2:00a.m. and wait one hour before resuming. Overnight passengers are often surprised to find their train at a dead stop and their travel time an hour longer than expected. At the spring DST change, trains instantaneously become an hour behind schedule at 2:00 a.m., but they just keep on going and do their best to make up the time.
An appropriate conclusion are words from Michael Shaw, “Since it is unlikely that DST will be removed completely, as it should be, enjoy those brighter barbecue summer evenings, but don’t believe that political hype!” (4)
Historical note- The idea was first suggested by Benjamin Franklin during his tenure as an American delegate in Paris. A well-known skinflint, Franklin calculated that thousands of pounds of candle wax could be saved with his idea. However, the idea did not catch on until World War I. (10)
References
1. Michael Downing, Spring Forward, (Washington, DC, Shoemaker & Hoard, 2005),
2. David Prerau, Seize the Daylight, (New York, Thunder’s Mouth Press, 2005)
3. Ryan Kellogg and Hendrik Wolff, “Does Extending Daylight Saving Time Save Energy? Evidence From an Australian Experiment,” University of California Energy Institute, CSEM WP 163, January 2007
4. Michael D. Shaw, “Spring Ahead Fall Back, Roll Over, And Play Dead,: What You Might Not know About Daylight Saving Time,” healthnewsdigest.com, March 12, 2007
5. Adreinne Kandel and Margaret Sheridan, “The Effect of Early Daylight Saving Time on California Electricity Consumption: A Statistical Analysis,” California Energy Commission, CEC-200-2007-004, May 2007
6. Matthew J. Lotchen and Laura E. Grant, “What’s the Point of Daylight Time?” mytimes.com, November 20, 2008
7. Thomas Kantermann, et al., “The Human Circadian Clock’s Seasonal Adjustment is Disrupted by Daylight Saving Time,” Current Biology, 17, 1996, November 20, 2007
8. T. A. Lahti, et al., “Transition into and out of daylight saving time compromise sleep and the rest-activity cycles.” BMC Physiol., 8, 3, February 12, 2008
9. Anahad O’Conner, “The Claim: Daylight Saving Time Can Affect Your Health,” nytimes.com, March 9, 2009
10. Richard H. Thaler and Cass R. Sunstein, Nudge, (New York, Penguin Books, 2009)
