by Mary Hrovat
I had my first experience with Daylight Saving Time when I was 9 or 10 years old and living in Phoenix. Most of the country was on DST, but Arizona wasn’t. I knew DST as a mysterious thing that people in other places did with their clocks that made the times for television shows in Phoenix suddenly jump by one hour twice a year. In a way, that wasn’t a bad introduction to the concept. During DST, your body continues to follow its own time, as we in Phoenix followed ours. Your body follows solar time, and it can’t easily follow the clock when it suddenly jumps forward.
When I moved to Indiana as a young adult, I was relieved that my new home, like Arizona, didn’t observe DST. The history of time zones in Indiana is complex. When I moved here in 1980, most of Indiana was on Eastern time. Because the state is on the western edge of Eastern time (and arguably ought to be on Central time), DST makes less sense for Indiana. We already have relatively late sunrises and late sunsets. Eastern time is one zone east of where we should probably be. We don’t need DST to effectively move us one time zone even further east.
Before standard time zones existed, all time was based on local solar noon. Indianapolis is closer to the center of the Central time zone than to the center of the Eastern time zone, as currently defined, and until 1960, the entire state was on Central time. However, for various reasons, the state crept into the Eastern time zone, first just half of it and then most of the rest. The exception is 12 counties in the northwestern and southwestern corners, which chose to be on the same time as nearby regions on Central time.
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I was saddened when Indiana adopted DST in 2006. My distress was compounded a year later, when DST was extended so that it covers about eight months of the year. It seems patently ridiculous for Indiana to set its alarm clocks to Atlantic time for two-thirds of the year. I also had more personal reasons for objecting to the change. I love twilight, and I don’t deal well with heat; in summer, I like to walk near or after sunset if I can. But when the sun sets at 9 or 9:15, a lot of the places I like to go or need to go close before sunset. I suspect one reason Arizona is not on DST is that sunset is welcome on blazing hot days. I also like being able to go stargazing before 10 or 10:30 at night.
In addition, the earlier start to DST means that as we climb slowly from the dark of winter to brighter mornings, the transition is interrupted by an abrupt return to the late sunrises of mid-winter. Of course, sunrise and sunset themselves don’t change abruptly; it’s only our clocks, and social expectations. Every year I resist moving my clocks in spring; I rely on my phone and laptop to keep me connected to people time and keep everything else set to standard time. Sooner or later, though, it becomes too hard to juggle two times, and I reluctantly have to make the switch.
This disconnect from the natural cycle of time is the thing that distresses me most about DST. I often feel that I don’t fit well into most social settings, and I can reasonably be described as neurodivergent. The natural world (including urban nature) is a stable, peaceful space for me. I love watching light and shadow changing slowly with the year; it helps me feel grounded and connected to something larger and more lasting than myself, or any human activity. The shift to DST intrudes on this deeply personal sense of connection.
Most of the people I talked to about Indiana’s adoption of DST in 2006 didn’t understand why I was so upset about it. “But those long summer evenings!” was a standard response. My answer to that is that Indiana has a fair amount of daylight after work hours on standard time. If you’d like even more time outdoors after work, you might consider asking or advocating for flexible work schedules. By leaving clocks alone, that approach would also benefit those who welcome sunset in summer, and those who would like to have sufficient light for morning bike rides before everyone’s out and about in their cars. That’s a lot to cram into a casual conversation, so I generally didn’t try to explain. And I couldn’t explain the most important point to me: the disjunct between natural time and clock time.
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I don’t see any sound rationale for DST. Personal preference for long evenings is clearly not a basis for a time system. DST is associated with economic benefits; chambers of commerce, businesses connected with leisure activities, and convenience store owners have lobbied for it. The desire to enable people to spend money is also a poor basis for a time system; in fact, centering economic policy on consumption is unwise.
Rationales based on safety (for example, the safety of children traveling to school) inevitably run up against the fact that at some times of the year, there’s not enough daylight to accommodate our existing scheduling practices. We’re apparently not willing to examine our unstated assumptions about these practices.
Benjamin Franklin was joking when he wrote that moving the clock forward would reduce the need to use candles, but DST is believed to reduce energy usage. If that was ever true, it’s not clear that it’s the case now, when reductions in electricity use for lighting may be offset by the increased use of air conditioning or heating. A study of electricity use in Indiana with and without DST found that DST actually increases electricity use slightly. (Another study showed a very small reduction in energy use associated with the current extension of DST.) A 1993 study found additional fuel consumption and pollution because of increased driving when daylight hours are shifted evening-ward. Even if energy use were significantly reduced by changing work hours, it would make more sense to make those changes at the workplace level without changing the clocks for everyone.
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There’s increasing evidence that DST is detrimental to human health. The annual switch to DST is associated with increases in heart attacks, strokes, fatal car crashes, workplace accidents, and emergency room visits. Various groups are especially sensitive to the effects of the change. Small children are more in tune with their bodies than with the clock, and the adjustment can be difficult for them and their caretakers. People with dementia sometimes lose touch with their sense of time and do best on a regular schedule; they’re also thrown off by the switch to DST. Those who have difficulty sleeping, especially those with a late chronotype (night owls) can also be more strongly affected (and more of us are night owls these days; see below). People with depression, anxiety, and substance abuse problems can have difficulties around the time change. Altogether, that’s a lot of people.
There’s been less research on the chronic effects of living on DST, but there’s some evidence that people don’t adjust to DST the way they would adjust if they traveled to a time zone east of them. After sufficient time in the new time zone, the human body starts to synch with local sun time. But local sun time stays the same even though the clock is moved eastward in March, and your body stays in synch with it. Although sleep timing may change (people often have to get up earlier whether they like it or not), it’s not clear whether circadian rhythms shift; two studies have shown that they don’t shift much. There’s also indirect evidence that DST has unhealthy effects that persist until we return to standard time.
Light and sleep are central to the effects of DST. Early morning light helps to maintain circadian rhythms, and decreasing light in the evening causes physiological changes that prepare you for sleep. On DST, many people are routinely attempting to get up and go to sleep before they’ve received the physical cues that elicit wakefulness and sleep. In addition, natural light cues are weaker in industrialized countries, and the effect of this is to delay the sleep-wake cycle. Thus, our lifestyle is pushing us to wake up and go to sleep later while clock time pulls us in the opposite direction. (It’s not just your screen time in the evening that disrupts your sleep; DST compounds the negative effects of blue evening light.) Loss of sleep is linked to higher risks of obesity, diabetes, high blood pressure, and depression. Many adolescents must get up for school before their body clocks are ready, even on standard time; they’re further hurt by being on DST, which is in effect for more than 5 months of a typical 10-month school year.
Interestingly, later daylight has been associated with a modest increase in physical activity in children, but mainly in Europe and Australia, not in the US.
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If I had to choose between the current standard time zones with DST or without it, I’d opt for ditching DST and using standard time year-round. But the current standard time zones aren’t ideal. I’m especially aware of this because I live on the western edge of a rather wide time zone. On July 31 in Bloomington, solar noon is at 1:52 p.m. EDT. Even on standard time, we’re 30 to 60 minutes behind the sun. The reason is that time zones use solar noon at a single longitude, the standard meridian, to establish clock noon across the entire east-to-west extent of the time zone. Thus, clock noon can differ from solar noon depending on where you are in the time zone. DST adds an hour to these differences on the western side of time zones, but time zones alone weaken the association between clock time and sun time (which is also body time). Living on the western edge of a time zone is associated with some of the same sleep-disruptive health effects as living on DST.
One of the fundamental problems with DST is that it adjusts clock time at the national level rather than social time at the local level. Every place on Earth gets a certain amount of daylight each day depending on the time of year. Daylight can’t be saved; sunshine needs no protection. The question of how we use daylight throughout the year (how we set our social clock) is one for communities to address. If we want children to travel to and from school during daylight hours, we should consider local sun times when setting school schedules. (If we want them to have ample time for physical activity, we should allow them plenty of recess time at school.) If we like having daylight before and after work, local sun times are important for arranging work hours.
I wonder what would happen if we weakened the association between clock time and sun time further—for example, by adopting a single year-round time zone for the entire continental United States. This may seem counter-intuitive, but my thinking is that we might benefit from shifting clock time for everyone away from the conventional hours we associate with certain activities. If we set standard continental US time to Universal Time (sun time at 0° longitude) minus 3 hours, for example, it wouldn’t make sense anywhere in the US for school to start at 8 a.m., work to start at 9 a.m., and so on. We would have a single unambiguous time across the continental US, which is the point of standard clock time, and we’d be forced to reconsider our social clocks, including the ways we assign activities to the daylight available where we live. It might be an opportunity to redesign our days on terms more suitable for human well-being.
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I’ve become increasingly aware of how much human misery is caused not by differences in ability, personality, or functioning, but by the fact that these differences aren’t accommodated well. In the context of time, for example, having a late chronotype (that is, effectively following a social clock that’s east of your body clock) is associated with poorer health. This probably doesn’t have anything to do with the chronotype itself but rather is due to the wear and tear of trying to adjust to a social world that doesn’t accommodate it well. Neurodivergent people, disabled people, and anyone else who doesn’t fit the mold will be familiar with this dynamic in other areas of their lives.
I think everyone struggles sometimes with the demands of our human-built world, which often doesn’t sufficiently support physical or emotional health for anyone. We force children to sit still and be quiet in school; we force ourselves to sit in chairs in offices or call centers, or maybe these days at home, for hours each day, or to spend our days under artificial light in warehouses or commercial kitchens. By and large, we live under the myth that periods of sustained mental and physical effort can be purchased from us as if they were cans of soup, without regard to our natural ebbs and flows. Artificial light is increasingly encroaching on our view of the night sky, an incalculably precious human birthright (darkness at night is also conducive to human health). We build and maintain car-centric cities, which isolate us, pollute our environment, and make it difficult or dangerous to move around under our own power. We’ve adapted ourselves to an industrial world by treating ourselves, to some extent, as machines.
We quote Mary Oliver’s advice to “Let the soft animal of your body love what it loves” because we need it so badly, because there are so many ways we deny our bodies what they need. The very cough drop wrappers give us pep talks on powering through illness. Might we begin to make the world more humane by letting the soft animals of our bodies sleep and wake by their own clocks?
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The article Why Should We Abolish Daylight Saving Time? (Till Roenneberg et al., 2019) is an interesting resource on the interactions between sun time, clock time, and social time.
Image by OpenClipart-Vectors from Pixabay
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You can find more of my work at MaryHrovat.com.