Daylight Saving Time
I can already hear the groaning. Daylight Saving Time begins Sunday morning, and many of us dislike it.
Like paying the milkman or dialing an operator, changing the clocks twice a year may soon become one of those bygone practices that baffles our grandchildren. As early as 2024, most of the U.S. may switch to permanent Daylight Saving Time. If that happens, the clocks will "spring forward" one hour next March, and never be fiddled with again.
Last week, the Sunshine Protection Act was reintroduced to Congress. This bill, which would make Daylight Saving Time permanent, was unanimously approved by the Senate last year, but not considered by the House. Nineteen states have already passed legislation saying they'll switch to permanent DST, if federal law permits it, and others, such as Oklahoma, are moving in that direction.
If you have strong feelings one way or the other about DST, it's not too late to take action. At the end of this newsletter I'll describe what you can do. My focus is on what statistics tells us about our options. The data are often misrepresented, and your congressional representatives, for example, may be misinformed.
What are the options?
1. Keep the status quo ("spring forward, fall back"), which currently happens everywhere except Hawaii, most of Arizona, and several U.S. territories.
2. Switch to permanent DST (move the clocks forward one spring, and never set them back). This is the option that seems to have the most bipartisan support. Practically speaking, given most peoples' schedules, permanent DST would mean less light in the morning, more light at the end of the day.
3. Switch to permanent standard time (never move the clocks forward). This option is advocated by the American Academy of Sleep Medicine and other health organizations, and there are hints that at least some members of the House are receptive to it. Practically speaking, this would mean more light in the morning, less light at the end of the day.
What do we want?
Polls consistently show that most Americans don't want the current system. The margin is typically around two-to-one in favor of giving up biannual clock changes. But there are competing views on what we'd prefer instead:
—A 2022 poll conducted by Monmouth University showed that 44% of Americans want permanent DST while only 13% want permanent standard time. Other polls have yielded similar findings.
—A 2021 poll conducted by the Associated Press and the National Opinion Research Center showed that 43% of Americans want permanent standard time while 32% want permanent DST. Other polls have yielded similar findings.
Both Monmouth and AP-NORC are highly respected polls. People who prefer permanent DST cite Monmouth or others like it. People who prefer permanent standard time cite AP-NORC or others like it. Which poll is right?
You're going to hate this answer, but I don't think either one should be trusted. I don't think we know the majority view.
The Monmouth poll was conducted in March, at the beginning of DST. The AP-NORC poll was conducted in October, near the end of DST. Some experts speculate that the timing of the polls influenced the responses. For instance, both polls might've reflected momentary grumpiness: some people may have stated a preference for whatever system they're changing to, because they don't want to make another change later. That interpretation would reconcile the apparently contradictory findings, but it still doesn't tell us how Americans feel most of the time. More data is needed to get at our "true" feelings. (In the Appendix I describe another reason why these polls are inconclusive.)
Although the majority view may be unclear, the federal government seems to be on the verge of approving permanent DST anyway, and many states have passed supportive legislation. Would this be a good thing?
Arguments for permanent DST
Supporters of permanent DST emphasize the benefits of having more sunlight available in the evening. Of course, the actual amount of light doesn't change. Rather, by adjusting our clocks but not our daily routines, DST gives us, in effect, an additional hour of light. The benefits of that extra hour are seen in studies of effects observed on March evenings, immediately after the clocks have been moved forward. Here's some of the evidence cited in favor of more evening light:
—fewer traffic accidents
—fewer robberies
—more exercise
—more consumer spending
—more energy savings (owing to less use of artificial light)
All of the effects are small and, as I'll explain below, some have been contested.
Arguments for permanent standard time
Supporters of permanent standard time focus on the need to stay closer to our biological clocks, which are attuned to the progression of the sun. According to this view, our circadian rhythms are disrupted when it's too dark in the mornings and too light in the evenings. Broadly, disruption of circadian rhythms is associated with a greater risk of obesity, cardiovascular disease, and mental health problems. More specifically, studies have linked DST to sleep disturbances, depression, and a temporary rise in the incidence of heart attacks and strokes.
Evaluating the data
You can already see why permanent DST would have the political edge over permanent standard time. Permanent DST has been linked to a variety of benefits relating to health, safety, consumer spending, and energy use. Permanent standard time has only been linked to health benefits.
There are further downsides to the permanent standard time data:
—Some of the data merely shows that time changes are harmful. In particular, shifts into and out of DST are both linked to sleep disturbances and adverse cardiovascular events. If DST were permanent, there would be no transitions, and these problems would not be expected.
—Some of the data is indirect or speculative. For example, studies linking disruption of circadian rhythms to health impacts don't always consider DST. The claim that forcing children to go to school in the dark may create safety hazards, although sensible, is only minimally supported by the evidence.
—Some of the data is anecdotal and can't be summarized as neatly as, say, a spike in consumer spending. (I don't mean to discount this data. My point is simply that people in fields such as agriculture and education have complex experiences with DST and their perspectives can't always be reduced to a bullet point.)
There's also an issue that's both practical and philosophical: Given the use of artificial lighting and screens, our daily routines are no longer closely connected to the rising and setting of the sun. Supporters of permanent standard time sometimes push the argument that what's "natural" is what's best, but that's arguably not always the case. Eyeglasses, polio vaccines, and electrical lights aren't natural, but they're worth having. Meanwhile, we also have methods for coping with technological disruptions of circadian rhythms. If you have difficulty falling asleep at night, one strategy is to avoid using screens before bedtime, and to keep your bedroom dark enough so that light doesn't suppress the natural secretion of melatonin. Over-the-counter melatonin supplements are also available. These represent compromises between the demands of civilization and our natural tendency to wake up at dawn and go to sleep when the sun sets.
At this point you're probably thinking that I strongly favor permanent DST. I do favor it, slightly, but as a retiree I have to admit there's not much at stake for me. I'm much more concerned that people with jobs, classes, kids at home, etc. make their voices known. At the end, I'll offer some conclusions that could be used by people on either side of the debate.
Some qualifications
Although I'm in favor of permanent DST, the empirical support for it is often overstated. Consider, for example, links between DST and reductions in traffic accidents. News organizations, as well as supporters of the Sunshine Protection Act, routinely claim that more evening light makes the roads safer. However, according to systematic reviews, some studies show immediate reductions in accidents after the shift to DST, while others show increases or no changes at all. This is not surprising. An extra hour of light may benefit drivers who've been working all day, but those benefits might be offset by greater fatigue as a result of getting up an hour earlier than usual in the morning. In some studies, accidents increase during the mornings following DST, presumably because more drivers are heading out the dark and/or they're more tired. And, although a small number of studies point to long-term reductions in traffic accidents following DST, the effects are small, and it's unclear whether these changes are due to DST or to changing weather conditions. Like everyone else, I'd love to say that we know what the impacts of permanent DST on road safety would be, but I don't think we know.
One last example. The data on energy consumption are especially complicated but do not support a simple connection between DST and energy savings. Although DST reduces reliance on electrical lighting in the evenings, it also increases seasonal needs for air conditioning in hotter parts of the country. There's no consensus on the net impact.
In sum, a permanent shift to DST might be more beneficial than a permanent shift to standard time, but the advantages of shifting to DST are sometimes overstated.
What should you do?
If you care about the prospect of a permanent shift to DST, contact your U.S. Congressional representatives and share your views. (See here and here or here.) While the Senate has unanimously supported the Sunshine Protection Act, interviews with members of the House suggest less consensus there.
Here are some points to keep in mind, regardless of your position on the debate:
1. It's not clear what the American people want.
As I mentioned earlier, poll results are conflicting, and the polls themselves are inconclusive. In my view, we should ask Congress to either oversee the gathering of more data, or to make a decision based on evidence of impacts rather than on assumptions about the "will of the people", which, in my opinion, nobody clearly knows.
2. The effect sizes are small.
I haven't seen any DST study in which the effects are moderate or large, statistically speaking. Small effects aren't necessarily unimportant. If a new legislation leads to even one less traffic accident, or one less heart attack, it might be worthwhile. The problem with small effects, in this instance, is that the outcomes are complicated and influenced by numerous variables. Accidents, robberies, health, spending – lots of variables have small impacts on these outcomes. Meanwhile, setting the clock isn't an isolated change. It also affects how people feel in the morning, how well they can see the road as they drive to and from work, how alert they feel on the job, etc. In my view, this means we should avoid the claim that shifting to permanent DST would be an overwhelmingly good thing. At best it might be a small good thing. I realize that's not highly persuasive, but it's closest to what the data tell us. (Perhaps the greatest advantage would simply be not having to worry anymore about changing the clocks that don't already change themselves.)
3. The Congressional record is lacking.
Senator Marco Rubio, who reintroduced the Sunshine Protection Act to the Senate last week, has created an official summary of the bill that cherry-picks studies, cites research that has been discredited or countered by alternative findings, and fails to acknowledge the downsides of permanent DST. Although I'm in favor of this bill – as were the Democratic Senators I voted for – the rationale for it isn't based anything close to a fair reading of the literature. The same can be said for the Congressional Research Service's most recent report on DST. (The CRS is a nonpartisan branch of the Library of Congress that provides members of Congress, their staff, and their committees with summaries of research and policy analysis.) So, whatever your view, let your representatives know about the data that supports it.
Thanks for reading! And thanks in advance to my daughter Cecilia for showing me, again, how to change the clock on my stove.
Appendix: DST poll questions
Here are the Monmouth and AP-NORC poll questions:
Monmouth: "...If the country was to choose one set time for the entire year, would you rather have the sun rise earlier in the morning and set earlier in the evening, or would you rather have the sun rise later in the morning and set later in the evening?"
AP-NORC: "As you may know, daylight saving time is the practice of setting clocks one hour later in the summer, so that the sun rises and sets one hour later than it would during standard time. During standard time, the sun rises and sets one hour earlier than during daylight saving time. Would you prefer to use daylight saving time all year round, standard time all year round, or switch back and forth between them?”
As I mentioned, Monmouth respondents tended to prefer permanent DST ("…the sun rise later in the morning"), while AP-NORC respondents tended to prefer permanent standard time.
You could speculate about how the wording of each question influenced peoples' responses. But, as with the timing of the polls, if the wording of questions matters, then we need more data to understand how people actually feel.
There's a deeper issue too. Both polls fail to mention all the other differences between standard time and DST that people care about. Think about what happens when DST kicks in this Sunday, for example. On Monday you'll probably feel like you've gotten up an hour earlier. If you're a parent, you may feel concerned that your child has to wait in the dark for the school bus. If you have a long commute to work, you might grumble about driving there in the dark (while appreciating the sunlit drive home).
The problem here is a common one with polls. Since the purpose is to gather data efficiently from large numbers of people, the questions as well as the answer options tend to be brief. In this case, they're too brief. An improved version of the questions would provide more context, allowing people to reflect on everything that comes with clock changes before answering the question.