Daylight saving time ended Sunday: 6 things to know about “falling back”

 In U.S.

On Sunday, at 2 am, clocks turned back one hour, heralding the end of daylight saving time for much of the country. The change shifted daylight back into the morning hours. For 9-to-5 office workers, it means saying goodbye to leaving work while it’s still light out. And for weekend workers, it meant an additional glorious hour of sleep on Sunday.

And yet there’s a lot of confusion about daylight saving time.

The first thing to know: Yes, it ends in the fall, just as the decrease in daylight hours starts to become noticeable.

Let’s sort it all out.

1) Why do we need to “save” daylight hours in the summer?

Daylight saving time in the US started as an energy conservation trick during World War I, and became a national standard in the 1960s. The idea is to shift the number of daylight hours we get into the evening. So if the sun sets at 8 pm instead of 7 pm, we’d presumably spend less time with the lights on in our homes at night, saving on electricity.

It also means that you’re less likely to sleep through daylight hours in the morning (since those are shifted an hour later too). Hence “saving” daylight hours for the most productive time of the day.

Overall: We agree, the name is kind of confusing.

2) Isn’t it “daylight savings time” not “daylight saving time”?

No, it’s definitely called “daylight saving time.” Not plural.

3) Does it actually lead to energy savings?

As Joseph Stromberg outlined in an excellent 2015 Vox article, the presumed electricity conservation from the time change is unclear or nonexistent:

Despite the fact that daylight saving time was introduced to save fuel, there isn’t strong evidence that the current system actually reduces energy use — or that making it year-round would do so, either. Studies that evaluate the energy impact of DST are mixed. It seems to reduce lighting use (and thus electricity consumption) slightly but may increase heating and AC use, as well as gas consumption. It’s probably fair to say that energy-wise, it’s a wash.

4) What would happen if daylight saving time were abolished? Or if it were extended forever?

Currently, the state of Massachusetts is in the early stages of considering a proposal to stay on daylight saving time year round. It involves shifting into Atlantic time — which is an hour ahead of Eastern time — and then staying there the whole year. (Atlantic “standard” time, and Eastern “saving” time are the same.)

The plan is a long shot. The Boston Globe explains that the Massachusetts legislature and the Department of Transportation would both have to approve it. And similar bills have failed in Maine, New Hampshire, Connecticut, and Rhode Island. But its proponents say Massachusetts would benefit by having more sunlight hours in the afternoon and evening throughout the year.

And it wouldn’t be the only state to not observe the changing of the clocks. Much of Arizona currently ignores saving time.

But why stop at Massachusetts? It’s worth thinking about what would happen if Congress abolished daylight saving time (or kept it going all year long).

Blogger and cartographer Andy Woodruff decided to visualize this with an excellent series of maps.

The goal of these maps is to show how abolishing daylight saving time, extending it all year, or going with the status quo changes the amount of days we have “reasonable” sunrise and sunset times.

Reasonable, as defined by Woodruff, is the sun rising at 7 am or earlier or setting after 5 pm (so one could, conceivably, spend some time in the sun before or after work).

This is what the map looks like under the status quo of twice-yearly clock shifts. A lot of people have unreasonable sunrise times (the dark spots) for much of the year:


Andy Woodruff

Here’s how things would change if daylight saving were abolished (that is, if we just stuck to the time set in the winter all year). It’s better, particularly on the sunrise end:


Andy Woodruff

And here’s what would happen if daylight saving were always in effect. The sunrise situation would actually be worse for most people. But many more people would enjoy after-work light — and there’s a strong argument to make that this after-work light is actually worth more. (More on that below.)


Andy Woodruff

(Note: The length of light we experience each day wouldn’t actually change; that’s determined by the tilt of Earth’s axis. But we would experience it in times more accommodating for our modern world. Be sure to check out the interactive version of these maps on Woodruff’s website.)

In 2015, Stromberg made the compelling case that the daylight saving time shift into the evening should be extended year-round. Having more light later could benefit us in a surprising number of ways:

  • People engage in more leisure activities after work than beforehand, so we’d likely do more physical activity over sedentary leisure activities. Relatedly, studies show that kids get more exercise when the sun is out later in the evening.
  • Stromberg also cites some evidence that robberies decrease when there’s more sun in the evening hours.
  • There could be economic gains, since people “take short trips, and buy things after work — but not before — so a longer DST slightly increases sales,” Stromberg writes.

5) Is daylight saving time dangerous?

A little bit. In the spring time, when we shift clocks forward one hour, many of us will lose that hour of sleep. In the days after daylight saving time starts, our biological clocks are a little bit off. It’s like the whole country has been given one hour of jet lag.

One hour of lost sleep sounds like a small change, but we humans are fragile, sensitive animals. Small disruptions in our sleep have been shown to alter basic indicators of our health and dull our mental edge.

And when our biological clocks are off, everything about us is out of sync. Our bodies run this tight schedule to try to keep up with our actions. Since we usually eat a meal after waking up, we produce the most insulin in the morning. We’re primed to metabolize breakfast before even taking a bite. It’s more efficient that way.

(There’s some good research that finds taking over-the-counter melatonin helps reset our body clocks to a new time. Read more about that here).

Being an hour off schedule means our bodies are not prepared for the actions we partake in at any time of the day.

One example: driving.

In 1999, researchers at Johns Hopkins and Stanford universities wanted to find out what happens on the road when millions of drivers have their sleep disrupted.

Analyzing 21 years of fatal car crash data from the US National Highway Transportation Safety Administration, they found a very small, but significant, increase in road deaths on the Monday after the clock shift in the spring: The number of deadly accidents jumped to an average of 83.5 on the “spring forward” Monday compared with an average of 78.2 on a typical Monday.

And it seems it’s not just car accidents. Evidence has also mounted of an increase in incidences of workplace injuries and heart attacks in the days after we spring forward.

6) How can we end daylight saving time, or extend it all year round?

That’s easy! Well, not really: All it would take is an act of Congress. But given the current pace of major legislation, I wouldn’t count on this happening anytime soon.

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