Daylight Saving Time explained: When the clocks change, why we do it, and what it means

The clocks on our smartphones do something bizarre twice a year: One day in the spring, they jump ahead an hour, and our alarms go off an hour sooner. We wake up bleary-eyed and confused until we remember what just happened.

Afterward, “Daylight Saving Time” becomes the norm for about eight months (And yes, it’s called “Daylight Saving” not “Daylight Savings.” I don’t make the rules). Then, in the fall, the opposite happens. Our clocks set themselves back an hour, and we wake up refreshed, if a little uneasy. 

Mild chaos ensues at both annual clock changes. What feels like an abrupt and drastic lengthening or shortening of the day causes time itself to seem fictional. Babies and dogs demand that their old sleep and feeding habits remain unchanged. And more consequential effects — for better or worse — may be involved as well (more on which in a minute).

Changing the clocks is an all-out attack on our perception of time as an immutable law of nature. It interrupts our lives in ways that are somewhat obscure precisely because they’re the norm. It’s reasonable to have questions: Why is something so weird considered normal? How does it work? Do we really have to do it? Will it ever stop?

And here are the answers.

Why do we do Daylight Saving Time? What does it mean?

The popular idea that Benjamin Franklin invented Daylight Saving Time is half-true. He wrote a humorous letter to the editor of The Journal of Paris in 1784 about accidentally waking up at 6 a.m. and discovering that — Surprise! — the sun had been shining early in the morning all along, and he’d been missing it by snoozing until noon. In the letter, Franklin crunches some numbers, and concludes that governments should use tax incentives to try and induce their people to be awake whenever the sun is shining, largely in order to save money on candles. In spirit, this is similar to the goals of Daylight Saving Time, but Franklin did not propose that everyone should change their clocks twice a year.

If you need a single name, British residential real estate developer William Willett who wrote the 1907 pamphlet “The Waste of Daylight,” was probably the inventor of DST — or as he called it “British Summer Time.”

A New Zealand entomologist named George Hudson had quietly proposed a similar idea a few years earlier in 1895, but Willett was a wealthy businessman who was eventually able to have his idea transformed into a formal parliamentary proposal in the UK, so I’ll grant him the credit over Hudson because his plan got results, but feel free to disagree with me.

Willett was an early riser and avid golfer, and so he had a fixation on what time the sun rose and set. With that in mind, he proposed two yearly time changing phases — one in April, and one in September. Willett’s more elaborate time change phase idea would have meant a series of four time changes in increments of 20 minutes each, stretched out over a four-week period. It was mind-bendingly complicated, but it would have lessened the abrupt impact. 

All that complexity probably makes Willett’s plan sound a little deranged, but keep in mind, this was meant to fix a problem that modern, clock-changing humans are only vaguely aware of: dusk comes annoyingly early in the warmer months in standard time. It’s warm, and there’s plenty of daylight in the day for extra golfing if you’re Willett, or extra bug-catching if you’re Hudson. And yet, all that bonus daylight is front-loaded into the morning when everyone is barely even awake yet. What a waste!

Willett never saw his proposal adopted in his lifetime. The year after Willett died, however, amid the resource constraints of World War I the United Kingdom put the one-hour-at-a-time clock-changing plan, not Willett’s more gradual, monthlong plan, into effect, calling it the Summer Time Act of 1916. But Britain only adopted DST after its wartime enemy, the German Empire, adopted it first. Initially, the purpose was to conserve coal for the war effort, but slowly, in fits and starts over the rest of the 20th century, most of Europe, much of the English-speaking world, some of Latin America, and a few other places formally implemented time changes. 

That brings us pretty much to the present. It’s estimated that about a billion people, or roughly an eighth of the global population, now have to deal with two annual time changes: One as the warmer months are coming on, to make the daylight hours in the longer days more usable, and once when winter is coming, because there’s no extra light to be juiced out of those hellish winter nights. 

Where does Daylight Saving Time happen, and when?

Without getting too detailed, here are most of the places where clocks get changed:

When the clocks change for end of Daylight Saving Time 2022

If you’re in the U.S., you’ll need to set your clocks back an hour on the morning of November 6 if they aren’t self-changing. If you want to see the time change in action, you can stay up the night of November 5, and wait until 2 a.m. November 6. At that time, turn your clock back an hour and, yep, repeat the hour that just happened.

For a similar demonstration in spring, in the wee hours of March 12 next year, wait until 2:00 a.m. and turn your clock ahead to 3:00 a.m. That missing hour simply disappears into a wormhole.  

Is Daylight Saving Time good?

There simply is no objectively correct opinion on Daylight Saving Time.

The economic benefits of the wartime clock adjustment were real and immediate, according to the book Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time by David S. Perau. The adoption of DST led to “increased overtime work,” along with, “reductions in power for electric lighting [that] averaged about 20 percent.” That 20 percent power use reduction corresponded to “a cutback of about 1 percent of the total coal used for all purposes in a year.” A one percent savings is huge.

Arguments against daylight saving, which robs light from the morning to give it to the evening, often revolve around concerns over school kids, who are forced to wait for their morning buses in the dark, potentially exposing them to crime and an increase in car accidents. Contrast that concern with a 2015 study by Brookings showing that DST reduces crime by pushing the cover of nighttime darkness back an hour, resulting in $59 million in savings per year in reduced robberies.

But the clock changes and their accompanying chaos appear to bring about real, and sometimes fatal, problems. A study on the autumn time change from DST back to standard time strongly suggests that the event triggers an 11 percent rise in acute depression among susceptible people. That same time change was also once associated with a sudden 24 percent rise in reports of heart attacks. Another study linked the other time change — the one in spring — to a 6 percent increase in fatal car crashes.

Which brings us to the rising movement aimed at locking in Daylight Saving Time, and ceasing the clock changes altogether.

Is Daylight Saving Time Permanent yet?

No.

59 percent of Americans favor a permanent change to DST. The new system would have a much less technocratic takeaway: It would just nudge time over an hour forever. The sun would be overhead not at 12:00 p.m. but at 1:00 p.m. This would result in more evening sun year-round, but also more morning darkness, which is why some experts who want to abolish the time change would prefer permanent standard time.

But here in the U.S., permanent Daylight Saving Time really might happen.

On March 15 of 2022, the U.S. Senate unexpectedly passed a bill called “The Sunshine Protection Act,” which may make it seem like Daylight Saving Time is on the verge of being permanent. Not so fast.

The bill is an interesting case study in American democracy. It was introduced on March 9, and abruptly passed six days later via something called unanimous consent. This means when it was brought up for a cursory initial vote, no one voiced any objections, so it passed without further deliberation. In the normally glacial United States Senate, this sort of thing almost never happens, according to Paul McLeod of Buzzfeed News. McLeod’s report on the passage of the bill notes that Senators Tom Cotton and Roger Wicker were among those whose stated beliefs were in opposition to ending the time change. Either of their votes should have rendered unanimous consent impossible, but they simply weren’t there to object. 

But the bill that passed so smoothly in the Senate still has to pass in the House of Representatives, and that’s not going to be so easy. It’s not partisan bickering that’s the problem this time around — Republican Marco Rubio and Democrat Ed Markey were the Senate bill’s biggest champions — but regional and logistical bickering. According to a July story in The Hill, representatives are conflicted about whether to lock in standard time or DST. Moreover, regions like Florida, where there’s plenty of morning sun are less worried about locking in DST, but in a place like Maine, where morning sun is scarce for much of the year, that’s a troubling downside.

In normal times, the House is where bills pass quickly, only to die in the Senate, but we’re in Wacky-land with this bill, so it may meet its fate in the House. A suitably strange end to a strange piece of legislation.

And if it doesn’t pass, we’ll probably have to keep changing our clocks, and confusing our hungry dogs, for years to come.