Technology: March 2018 Archives

It is the first day of DST in the United States and everyone is groggy and cranky and wondering why we bother with changing the clocks twice a year. There are the usual calls to go to DST and stay there forever, or stay with standard time forever.

The last two Novembers I've spent some time in a place that doesn't have DST: the Australian state of Queensland. Australia has three principal time zones: Australian Western Standard Time (GMT+8 hours); Australia Central Standard Time (GMT+9.5 hours); and Australian Eastern Standard Time (GMT+10 hours). But from the first Sunday in October to the first Sunday in April, the south-central and southeastern states go on DST, while Western Australia, the Northern Territory, and Queensland remain on standard time. During this period you have the strange situation where you can drive 70 miles due south of Brisbane, and it's suddenly an hour later.

On November 30, late spring in Brisbane, Queensland's capital, dawn (civil dawn) comes at 4:18 am and dusk ends at 6:54 pm. On the longest day of the year, dawn comes at 4:23 am and dusk ends at 7:09 pm. For most people, that means 90 minutes or more of daylight while you're still trying to sleep, and yet it still gets dark not long after supper. Many Queenslanders would like to move that hour of early morning light to a more useful time.

As bad as at is to have the sky brightening when it should be oh-dark-thirty, Brisbane, a subtropical city with a relatively small fluctuation in the length of days over the course of the year, doesn't get the worst of it. The farther you get from the equator, the higher the latitude, the longer the days and the more sunshine is wasted. In Hobart, Tasmania, dawn would break on the solstice at 3:53 am without DST, but DST pushes that to 4:53 am and pushes nightfall from 8:24 pm to 9:24 pm -- more time after work for outdoor activities.

So if the problem is the distribution of sunlight around the work day, is there another way to solve it?

Idea #1: Move to DST permanently. But then, when you get to late autumn and winter, there's no sunlight at as people are going to work and school. If we still had DST in December, dawn would break at 8 am in Tulsa.

Idea #2: Stay on standard time permanently and move business hours to improve the amount of daylight after work. The challenge here is unpredictability. Some businesses would adjust hours, some wouldn't.

Idea #3: Designate sunrise on any given day as 6 am and reckon hours from that point of reference. A business that opens its doors at 8 am would always be starting two hours after sunrise. One problem with that idea is the same problem that led to the creation of time zones in the first place, when every town measured time by local noon; drive a few miles east or west and your watch would suddenly be off by a minute. Measuring time by sunrise would add a north-south variation to time calculation. It was bad enough to have local time variations when we could travel at 60 mph, but imagine the chaos dealing with local time variations now that we can communicate at the speed of light.

It turns out that moving clocks forward an hour in the spring and back in the fall is a pretty good compromise between all these competing concerns.

UPDATE 2025/03/09: A 2022 Time article remembers the two-year experiment with year-round Daylight Saving Time that began in January 1974, but was terminated that October. It was one of several energy-saving initiatives designed to cope with the Arab Oil Embargo following the USA's assistance to Israel during the 1973 Yom Kippur War; the 55 MPH nationwide speed limit was another, much hated and ignored, energy-saving attempt. Shortly after the clocks changed, there were accidents involving children walking to school in the dark.

In 1966, the Uniform Time Act set DST from last Sunday in April to last Sunday in October. In 1987, the start of DST was moved to the first Monday in April, and, since 2007, DST in the USA has begun on the second Sunday in March and ended on the first Sunday in November.

David Prerau, author of Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time, told Time that he favors the twice-yearly clock change:

I personally think that the current system that we have is an excellent compromise, between having Daylight Saving Time most of the year, but eliminating all the negatives of Daylight Saving Time in the winter. For the saving of that one hour of sleep in March, [you'd be] getting four months of dark mornings and cold mornings in November through March. So that's why I think the current system is better.

As permanent DST and permanent Standard Time are being debated again, I shared this BatesLine article on Facebook and X (Twitter). Here's how I summarized it on Facebook: The problem is the distribution of daylight around the work day. You want some daylight before work and school, but not too much. You want as much daylight as possible after work. Changing the clocks twice a year is the most orderly way to accomplish that. Permanent DST means dark before and after work in the winter. Permanent standard time means too much daylight when you're still trying to sleep in the summer.