Daylight saving time: yes or no?

POSTED: 03/11/14 12:12 AM

For days after “springing forward,” many of us feel a little jet-lagged and cranky. And the research is piling up to show that the time change affects more than our mood. It changes energy use, health, worker productivity and even traffic safety.

Does daylight saving time do more harm than good? In St. Maarten no one has ever even thought about this issue, as far as we know. Here are a couple of viewpoints about daylight saving time from the New York Times.

Steve Callandrillo, a law professor at the University of Washington School of Lae: “Extending daylight saving time year-round would save lives, reduce crime, save energy and stop Americans from losing sleep each time we switch our clocks.

First, darkness kills. Delaying sunset by an hour would save over 350 American lives annually, by reducing traffic fatalities during the evening. The change from daylight to twilight causes a 300 percent increase in fatal vehicle-pedestrian crashes, and the evening rush hour produces twice as many accidents as morning (nearly everyone is awake and moving about in early evening; whereas many are still asleep at sunrise).

Second, criminals love darkness. Numerous types of crime, including robbery, assault, motor vehicle theft and juvenile crime, peak during the early evening hours once the sun sets, while the corresponding rates are low during morning. Criminals are simply late to rise and late to bed, and we should take advantage of it by removing one hour from their workday.

Third, energy is saved by daylight saving time. Why? There is greater use of fossil fuels and electricity during evenings than mornings (because more Americans are awake). Hence, shifting sunlight to the evening causes a reduction in evening peak load, which outweighs a small increase in the early morning load caused by daylight saving time. This was the primary reason that the U.S. moved to year-round daylight saving time during World War II and the 1970s oil crisis.

Fourth, the switching of the clocks during fall and spring is concerning. Studies show a significant increase in traffic fatalities for the week following the spring time change (after we lose an hour of sleep), and shockingly the same result after we gain an hour in Fall. Why? Because altering sleep cycles negatively impacts health, coordination and alertness. This impact extends even to financial markets: on Mondays after the time changes, the NYSE, AMEX and Nasdaq exchanges average a one-day loss of $31 billion.

There are only so many hours in the day — we must take advantage of them the best we can.”

Not everybody agrees with this point of view. This is the opinion of Mathew Kotchen, a professor of economics at Yale University: “If you ask someone why we have daylight saving time, the most likely answer you’ll hear is that we change the clocks to help farmers. But daylight saving time has nothing to do with agriculture, except that farmers have historically opposed it, preferring morning sunlight to darkness when, say, milking the cows.

The annual time changes are about energy conservation. That is why daylight saving time exists in the United States and dozens of other countries, affecting more than 1.6 billion people worldwide. The argument, dating back to Benjamin Franklin and others before him, is that changing the clocks — with a spring forward and fall back — will decrease energy consumption because more sunlight in the evenings will reduce the need for artificial illumination.

There are certainly benefits, but energy savings is not one of them – a tradeoff to acknowledge as we enjoy an extra hour of sunlight on those long summer evenings.

But does this actually save energy? Recent studies suggest it has the opposite effect. One study that I worked on took place in Indiana, where daylight saving time was first instituted statewide in 2006. We found that the time change increased residential electricity consumption by 1 percent over all, with monthly increases as high as 4 percent in the late summer and early fall. The consequence for Indiana has been higher electricity bills and more pollution from power plants.

The reason is that daylight saving time reduces demand for residential lighting, yet increases demand for heating and especially cooling. So, while Benjamin Franklin’s argument still applies to lighting, the more important effect today comes from air conditioners. And in regions where demand for air conditioning is greater and growing, daylight saving time is likely to increase electricity use even more. Arizona, one of the hottest states, may have it right by not changing the clocks.

Of course, many people favor daylight saving time for reasons unrelated to energy, one of which is more time in the evenings for outdoor leisure. But many others find the switch disruptive and would prefer the early morning sunlight. One unifying theme I have found since conducting research on daylight saving time is that virtually no one has a neutral opinion on the subject.

As the debate continues this year, readers and policy makers should keep in mind that despite its intended effect, a growing body of evidence reveals that daylight saving time increases rather than decreases energy consumption. There are certainly benefits, but energy savings is not one of them – a tradeoff to acknowledge as we enjoy an extra hour of sunlight on those long summer evenings.”

And then there is the health aspect, as Shelby Harris points out. She is the director of the American Behavioral Sleep Medicine Program of the Sleep-Wake Disorders Center at Montefiore Medical Center.

“The human circadian clock is supposed to gradually adjust over the course of a season, with sleep and wake times slowly changing in response to the changing length and intensity of sunlight. But each year daylight saving time begins, we lose one hour of sleep – shifting our internal clocks faster than nature intended. One hour may not seem extreme, but we can’t reset our circadian rhythms as easily as we change the time on the microwave.

The human body does not readily or easily adapt to jarring changes in the alarm clock.

Scientists have connected a number of health consequences with the start of daylight saving time. Swedish researchers reported a 5 percent greater risk of heart attack in the three days immediately after the spring time change. Risk of heart attack is generally highest in the early morning year-round, but “springing forward” causes a sharp increase in early morning heart attack rates because of the earlier-than-usual wake times when the body’s cardiovascular state is least steady and more vulnerable to stress. When daylight saving time ends in the fall and we gain an hour of sleep, incidence of heart attack briefly falls below normal.

Even one hour of lost sleep affects many areas of functioning – decreasing motor function, memory and mood. After the spring time change, traffic accidents are more frequent and workplace injuries are more common. In the first few weeks after the “fall back,” suicide rates sharply increase. However, fewer vehicular accidents occur during daylight saving time, when the daylight hours are extended.

Considering productivity, energy use and many other societal factors, the pros and cons of daylight saving time are many and varied. But it’s clear that the human body does not readily or easily adapt to jarring changes in the alarm clock. We could keep daylight saving time or not, but if health and safety are the deciding factors, we should stop switching back and forth.”



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