LLBBL Blog

LLBBL Blog

Day 21: "DST is Dumb"

Most people think daylight saving time has something to do with farmers. It doesn’t. It never did. The farmers, in fact, hated it. DST shifts the workday by an hour, but it doesn’t shift the cows or the dew, and farmers fought against it for most of its existence.

DST was invented for lighting. Specifically, for coal. Germany adopted it in 1916, during the First World War, to push evening daylight an hour later so workers would burn less coal lighting their homes after dinner. Britain, the US, and most of Europe followed within two years. Energy savings. That was the entire pitch.

In 1916, this was a defensible bet. Lighting was the dominant residential electricity load. Bulbs were inefficient. Air conditioning didn’t exist. Refrigeration was rare. If you shifted clock-time so people went to bed before they turned on the lights, you measurably saved fuel.

In 2026, none of that is true. Lighting is about 10% of residential electricity use, down from above 40% a century ago. An LED bulb uses about a tenth of the energy of an incandescent. The dominant loads now are heating, air conditioning, and always-on electronics, none of which care what time the sun sets.

We’ve measured this. The cleanest study is Matthew Kotchen and Laura Grant’s 2011 analysis of seven million Indiana electric bills, before and after the state mandated DST statewide in 2006. The result: DST increased residential electricity demand by about 1%. The lighting savings were small, and they were more than wiped out by colder, darker mornings (more heating) and longer sunlit evenings (more AC).

So the entire reason DST exists no longer applies. The thing it was supposed to do, it doesn’t do anymore. Or it does the opposite.

That should have ended the conversation. It didn’t.

The price we pay for nothing

Here’s where it gets dark.

The people who hate DST the most are not the cranks. It’s the cardiologists.

In 2008, two researchers at the Karolinska Institute pulled the entire Swedish national heart-attack registry going back to 1987 and overlaid the DST transition dates. In the first week after the spring transition, heart attack incidence rose by about 5%. The first three days carried most of the spike. Working-age people were hit harder than retirees, which the authors took as evidence that the cause wasn’t the time change itself, but the combination of the time change with having to get to work.

A 2016 Finnish study by Sipilä, Ruuskanen, and colleagues found the same pattern for strokes: roughly 8% elevated risk in the two days after spring forward.

Traffic deaths follow the same curve. Josef Fritz’s 2020 analysis of 732,000 fatal US crashes pinned the spring-forward spike at about 6%. The mechanism is what you’d guess: sleep-deprived drivers, dark morning commutes, more pedestrians out at twilight.

This is a population-scale public health intervention that runs twice a year, that nobody voted for in any meaningful sense, that we’re administering to ourselves because of a coal-conservation policy from the First World War.

The deeper problem: social jet lag

There’s a more chronic effect that doesn’t show up in the spring-Monday data because it runs all year. Sleep scientists call it social jet lag, the persistent misalignment between your body’s circadian clock (anchored to actual sunlight) and your social clock (anchored to whatever the wall says).

DST permanently offsets these by an hour for the months it’s in effect. Your body, which is exquisitely sensitive to morning light as a circadian cue, gets pushed an hour off its natural entrainment. The research is correlational, not causal, but the associations are alarming: increased depression risk, higher BMI, worse academic performance in students, reduced productivity.

This is why every major sleep medicine organization has come to the same position. The American Academy of Sleep Medicine, the European Sleep Research Society, the AMA. They all want the biannual switch ended. And they want it ended toward standard time, not DST. We’ll get to why tomorrow.

So why are we still doing this?

Polls consistently find that about 7 in 10 Americans want to stop switching the clocks twice a year. That number has been steady across decades. There is, on this one specific question, an unusual degree of national consensus.

And other countries have just done it. Mexico ended DST in 2022. Iceland, Russia, Turkey, Argentina, and a long list of others abolished it years or decades ago. The European Parliament voted to end DST across Europe in 2019. (Implementation has stalled in Brussels, but the vote happened.) The world has a working playbook for “stop switching.” We just don’t use it.

The reason it persists in the US is not that people want it. It’s that the question of what we’d switch to hasn’t been resolved, and Congress can’t agree on anything anyway. (I’m starting to think we should rename them. The Incongruous, maybe.) Without a deal on the destination, the status quo wins.

DST should have died forty years ago, when central air conditioning replaced lightbulbs as the thing your house actually runs on. We’re keeping a public-health intervention because two camps can’t agree on which version of fake time we should freeze.

Time should be time. Just pick one. Stop switching.

Tomorrow: the political fight between permanent standard time and permanent DST. Two camps, both confident, with the strange fact that the camp the data points to is the one losing.

Sources

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