For those unfamiliar with U.S. timekeeping, we “lost an hour” of sleep last night, at least for those who slept according to clock time. Immediately after 1:59:59 in the morning, it was 3:00:00. We effectively changed into a different time zone, one hour east, and we do this switching forward and back every year. A lot of people don’t like Daylight Saving Time (or, in Europe, Summer Time) because it effectively “tricks” people into waking up an hour earlier, relative to solar time. If you wake up at 7:00, you’re actually forced to wake up at 6:00 for the majority of the year (DST is active for eight months out of the year, meaning that it is actually the usual time regime and winter/standard time is the special one).
On paper, Daylight Saving Time sounds really stupid– really, why on earth would we inflict that sort of unnecessary complexity on our timekeeping system? If it didn’t exist, and were proposed now, the idea would be rejected, and possibly for good reason. Benjamin Franklin proposed it as a joke, commenting on the unused daylight wasted by Paris’s nightlife culture. That said, I’ll go on record and be somewhat controversial. I like it. Its drawbacks are serious but I think that its advantages are numerous, as well. Sure, I know that there are a number of intelligent reasons to oppose DST, but I also have an emotional attachment to the 8:45 pm summer sunsets of my childhood. I “know” that time is arbitrary and stupid and that “light at 9:00 pm” means nothing because we invented these numbers and are really calling 8:00, 9:00. While I oppose this phrase when it is overused, time-of-day and especially daylight savings time literally are social constructs. They exist simply because follow the customs.
So let’s talk about Daylight Saving Time, and I’ll try to explain why it’s a good thing.
It’s not about energy saving. It’s cultural.
The evidence is pretty strong that Daylight Saving Time doesn’t save energy. Nor does it waste energy. On the whole, energy use is unaffected by it. Discretionary lighting just isn’t a large enough component of our energy expenditure for it to matter. Rather, we use Daylight Saving Time because (contrary to a vocal minority) most of us actually like it. Or, more specifically, we like the results of it. No one likes the transitional dates themselves, but in exchange for two very annoying days each year, we get (at typical latitudes):
- one hour less “wasted” morning daylight in the summer.
- sunset after 6:00pm at the peak of autumn (late October).
- sunrise before 8:00am in the depths of winter, because we transition back to standard time.
To make my argument that DST is cultural, just look at the dates when the transitions occur: mid-March and early November. Relative to daylight availability, this is inconsistent because there’s a lot less daylight in October than in early March. It’s asymmetrical, but it makes sense in the context of typical weather. In October, it’s still warm. In early March, it’s often cold. The transition dates are anchored to temperature, which affects human activity, rather than the amount of daylight.
Most people who oppose DST would prefer to make the summer time regime permanent. It’s not that they care about having “12:00″ (again, as defined by humans) be less than 30 minutes away from mean solar noon. They just don’t like the semi-annual change-over. So why don’t we just “make DST year-round” by moving one timezone to the east? The reasons, again, are cultural and come down to, it would really piss people off.
Year-round DST is (possibly) a bad idea.
I believe that the case for DST is strong. Sure, if you’re luckier than most people and have full control of your schedule, you’re likely to think it’s stupid. Why fuck with the clocks twice per year just to prevent people from “wasting” daylight? Shouldn’t people for whom that is some kind of issue just wake up earlier?
Most people, however, don’t control their schedules, especially when it comes to working hours. DST isn’t for people who can work 7-to-3 if they so choose. It’s not for freelancers who work from home or for people who set their own hours. It’s for people who have to be in an office or a retail outlet till 5:00 or 6:00 or 7:00. It’s to give them some daylight after work, especially in the spring and fall when natural light is not so ample. For them, that extra hour of after-work daylight matters.
In the winter, however, those people are going to be working until dark regardless of the time regime. Year-round DST would punt the typical winter sunset from 4:30 to 5:30, which isn’t a meaningful gain for them. They’d still go home in twilight and eat dinner in darkness. Moreover, it’d put the typical winter sunrise after 8:00. They’d be waking up and going to work in the dark, for no gain. With non-DST or “winter” time, they’re at least able to get some daylight in the morning. That can make a large difference when it comes to mental health and morale, because peoples’ satisfaction with work plummets if they don’t get some daylight on at least one side of their working block.
This has everything to do with how humans react to nominal time, and nothing to do with natural design. There is, of course, absolutely no natural basis for changing the clocks. It is, I would argue, a good thing that we do so, but our reasons for doing it are connected entirely to our social construct of time.
Yes, this is unnatural.
Daylight Savings Time might seem ridiculous because it’s so unnatural. Nature doesn’t have any concept of it, and it’s an active annoyance for farmers whose animals’ circadian rhythms don’t respond to our conception of time. This, I concede. It’s not natural to change the way we keep time by exactly 1/24th of a day (a fraction that matters to us for archaic reasons) twice a year. Also, we choose our transition dates based on approximate average temperature rather than daylight amount– specifically, keeping DST into late fall when the days are short but it is still warm– makes it obvious to me that this thing is cultural to begin with.
That said, the clock isn’t natural. Left to our own devices, we’d probably rise about an hour after sunset and go to sleep about two hours after sunset, with a 3- to 4-hour period of wakefulness between two spells of sleep (biphasic sleep). Where we evolved, there wasn’t much seasonality, so this probably didn’t change much over the course of the year, but it had to be changed once people moved north (and south) into the mid-latitudes.
If we were to focus on one geographic point, the ideal clock wouldn’t be anchored based on noon (12:00) but on sunrise. In a way, the original Roman hour achieved this, because an hour was exactly 1/12 of the duration between sunrise and sunset, causing it to vary throughout the year. For modern use, we wouldn’t want a variable hour but it would be pretty useful to anchor sunset to 6:00 exactly. This way, people can schedule their time according to how much light they need in the sky to awaken happily, rather than live in a world where “8:00 am” is just after sunrise (and, if it’s cloudy, still fairly dark) at one time of the year and bright mid-morning at a different time of year. That said, the “anchor sunrise to 6:00″ concept is actually pretty ridiculous, because it wouldn’t just require longitudinal timezones, but latitudinal ones as well, and they’d vary continuously throughout the year. If this were done, the actual time difference between Seattle and Miami would be 1 hour and 42 minutes at the height of summer, but 3 hours and 52 minutes in winter. That’s clearly not acceptable. There isn’t a sane way to come up with a time policy that stabilizes sunrise at, or even very close to, 6:00 in the morning. The system we have is probably the optimal point in the tradeoff between local convenience and global complexity. It imposes some complexity, and that’s why almost no one’s entirely happy with our time regime, but it also (a) prevents egregious “waste” of daylight in the summer, with the understanding that few people will wake before whatever time we call “6:00″, while (b) minimizing the number of people who have to commend and finish work in darkness by realigning political time with solar time in the winter.
Of course, there is the bigger question…
Will we, as a species, outgrow Daylight Saving Time? We only need it because so many of our recurring commitments (in particular, work) are tied to the clock. Unless there is jet lag, people on vacation don’t care if the daylight occurs in the morning hours or evening; they’ll just wake up at whatever time is appropriate to their activities. In 50-100 years, humanity will either have advanced into a leisure society where work is truly voluntary (as opposed to the semi-coercive wage labor that is most common, and still quite necessary, now) or destroyed itself: the technological trends spell mass unemployment that will lead either to abundance and leisure, or to class warfare and ruin. I don’t know which one we’ll get, but let’s assume that it’s the better outcome. Then it’s quite possible that in 2115, schoolchildren (unfamiliar with the concept of people being stuck in offices for continuous 8-12 hour periods) will learn that the people of our time were so tied down to others’ expectations that they had to change the clock twice per year just to align their working lives and seasonal daylight availability in a least-harmful way. They’ll probably find it completely ridiculous, and they’ll be right. All of that said, we live in a world where the social construct of clock time matters. It matters a lot: we’d have a lot more seasonal depression if we made people go to work and leave work in darkness, so we align our clocks to solar noon in the winter to avoid too-late (after 8:00) sunrises. But it’s also remarkably difficult to get people to wake up at a time which they’ve been conditioned to think is early, so we jerk the clocks ahead to avoid wasting daylight during the warmer seasons. From an engineering perspective, and with a focus on our needs as humans right now, I think that the system that exists now is surprisingly effective. It has some complexity and that’s annoying, but only a moderate amount relative to what it achieves.
