Spring forward!

That exhausted and off-step feeling can only mean one thing. Daylight Savings Time is back! For those of you who do not have the privilege of living in a place where DST is observed, let me tell you, there’s nothing like changing the clocks twice a year to be reminded that marked time is ultimately a human construction. And not even a consistently observed one - Iceland and Kyrgyzstan observe DST year-round, most tropical nations don’t observe it at all, countries in the Southern Hemisphere observe DST during their summer (Northern Hemisphere winter) and while DST observance has been standardized throughout the European Union, European DST and North American DST do not start or end at the same times.

Let’s start with exactly what DST does. In temperate regions, day length changes with the season - everyone knows that, but it’s helpful to think about exactly how this works. In New York City, the sun rose at 7:20 AM and set at 4:39 PM on January 1st, 2012. A month later, the sun rose at 7:06 PM, and set at 5:13 PM. A month after that, the sun rose at 6:29 AM, and set at 5:47 PM. In the absence of DST, we can assume that on April 1st, sunrise would be around 6 AM and sunset a little after 6 PM, and by June, on the eve of the summer solstice, the sun would be coming up at around 5 AM and setting shortly after 7 PM. In the United States, at least, most people start work between 8 and 10 AM, and end work between 4 and 6 PM. At this point, you can see how that first hour or two of daylight in high summer could be considered “wasted”. Additionally, humans are not nocturnal, many leisure activities take place after work, and the desire for more daylight towards the end of the day is understandable.

None of these are the stated reason for DST, however. The stated reason would be energy conservation. In fact, up until the 1960’s, DST was only instituted nationally in the US during times of war. Other than that, some states and municipalities had DST, some did not (those of you who have attempted to travel in Indiana during the summer will be aware that this phenomena persisted well into the present). In 1966, DST was instituted nationally (with local exceptions), extending from late April to late October. During the energy crises in the 70’s, DST was extended to all year, and in 2005, DST was expanded to its current early March to early November form.

How does DST save energy? Well, the idea is that with daylight expanding further into waking hours, people are less inclined to turn on lights (which in turn saves electricity). People are also less likely to be inside watching TV or on the computer if its light out (a distinction which has broken down somewhat in this age of laptops and smartphones). That’s the theory, then. Does it actually work? 

Maybe, maybe not. An initial study done in the 1970’s stated that DST would reduce energy demand/consumption by one percent nationally. On the other hand, a study from Indiana demonstrated that, in Indiana, at least, DST actually increases energy consumption. By expanding daylight further into the evening, people are more likely to be home during periods of high solar insolation, and correspondingly higher indoor temperatures, and more likely to run their air conditions. And, when DST extends later (or earlier) into the year, the cold, predawn hours extend further back into when people are home before work, home heating costs increase. The home heating effect was found to be stronger - something to consider when contemplating further extensions to DST.

Speaking of extensions...all right, so the point of DST is to get people out of the house in the evenings, enjoying the sunlight and not using their televisions, lamps, and computers. This makes sense for high summer (particularly when there is clearly an extra hour or so of daylight to play with), but why on Earth do we have DST for all of April and October? What was the rationale for the 2005 expansion?

For that, we need to go back to 1986. That was the year when Congress expanded DST to cover the entirety of April. After that, the precedent was set for further expansions. Now, let it be said that the “bankrolled by the candy industry” conspiracy about the expansion is not exactly grounded in fact.It is true, however, that to some extent the bill’s passage was due to the massive lobbying effort expended on behalf of the barbecuing, sporting goods and convenience store lobbies, all of whom benefit from expanded daylight in the evenings. On the other hand, the bill’s stated goal was to cut pedestrian fatalities during the evening rush hour by expanding daylight hours, a laudable goal (although a goal may better have been achieved by allocating funding to address potentially deadly shortcomings in pedestrian access. Either way, we would appear to be nearing diminishing returns on any further expansions of DST. So, enjoy the extra hour of daylight in the evenings, but I don’t recommend any effort to bring daylight savings to January.