Quidquid latine dictum sit, altum videtur

April 8, 2002

Daylight savings time: Is there a point?

Here in New Jersey, it’s daylight savings time again. As always, we lose one hour of sleep, adjust our ever-increasing number of household clocks and clock-containing appliances, and wonder what, exactly, the point of all this is.

Time, of course, has no natural structure and can be divided up and numbered in any arbitrary fashion. It’s convenient for us to use days and years in our measurements, since they correspond to major cycles for ourselves and the world around us, but pretty much everything else is up for grabs. The division of the day into 24 equal parts is not at all an obvious decision (and there are plenty of proposals for alternate schemes), and that doesn’t even address the question of which part to declare “first”. The Egyptians began the day with the sunrise. The Hebrews began it at sunset. Astronomers liked to use noon. We use midnight, but not the “actual” midnight (when the meridian of the sun is exactly on the other side of the world). Instead, we divide the world into zones, and declare midnight to occur at a specific time in each zone when compared with the time in Greenwich, England.

Daylight savings time throws the system further out of whack, but for a good, somewhat obsolete cause. Here in the northern hemisphere, the days get longer as we approach July. That means the sun sets later and rises earlier. Back when artificial light was limited to setting things on fire, people figured they could take advantage of the earlier rising sun by getting up earlier. This would effectively give them extra hours of sunlight during the day. There were two basic schemes available. First, they could get up at an earlier hour as the sun rose earlier. Alternately, they could get up at the same time, but shift the numbers around to make the sun rise and set at later times.

Apparently, they decided it was easier to muck around with people’s clocks than to get up earlier. (Well, they’re still getting up earlier, but it doesn’t seem earlier because the number is the same.)

In our modern age, when we use artificial light in our office buildings even when the sun is intensely bright outside simply because we can (or because the architect didn’t consider the soothing natural light of the sun to be important to the people inside the building), the need for daylight savings time may seem less than apparent. What, we might ask, does it matter if the sun rises at 6am instead of 7am and sets at 6pm instead of 7pm?

It’s not an easily answered question. I certainly enjoyed coming home from work in daylight, which only happened during daylight savings time. People then might ask, why not have it always be daylight savings time? The problem there is that during the winter the sun rises later and later. Switching back to standard time ensures that we don’t drive to work in the dark (unless we have a long commute).

There’s still the question of why we don’t keep the numbering of hours constant but simply do things explicitly earlier during the summer. A quick consideration of that policy suggests that it would be even more confusing. People with flex-time wouldn’t have problems, since they could simply come in and leave earlier, but would 9-to-5 people become 8-to-4 people in the summer? Would all the TV schedules shift up an hour in April? Would stores open and close an hour earlier?

Some people would shift schedules and some wouldn’t. There probably wouldn’t be a single date when the switchovers happened. It’s hard to say whether such a world would be more or less confusing than our own. (Consider that all the effects of daylight savings time I’ve mentioned are reversed in the southern hemisphere—and largely irrelevant in the tropics.) #