The case for standard time

Standard time is the setting that matches the sun

This is definitional, not empirical, which is why it is the strongest thing on the page. Standard time exists to put clock noon near solar noon. Daylight time deliberately offsets it by an hour. Across the country, standard time sits closer to solar time than daylight time does — the exceptions are a handful of places at the far eastern edge of a zone, like easternmost Maine, where the clock already runs behind the sun.

If you think the clock should describe where the sun actually is, you have already picked standard time, and no study is going to change your mind. Everything below is for people who want a reason beyond that.

Willett wanted an hour of evening light for golf. Germany wanted coal for a war. Neither is a reason we should still be doing this in 2026.

The history is worth knowing because it is so much thinner than people assume. William Willett self-published the idea in 1907, proposing eighty minutes across four Sunday steps, and he died before anyone adopted it. Germany and Austria-Hungary went first in April 1916 to save coal. Britain followed a month later, the United States in 1918. Benjamin Franklin did not invent it — his 1784 letter was a joke about waking Parisians with cannon fire.

The expert consensus is not split. It is unanimous.

We went looking specifically for a scientific body that endorses permanent daylight time, because a one-sided literature usually means somebody has not looked hard enough. There isn't one.

The title of the AASM's 2024 statement is the argument in one line: Permanent standard time is the optimal choice for health and safety. More than twenty organizations have signed on to that position, including the National PTA and the National Safety Council.

The counterweight, stated fairly: these are position statements, not systematic reviews, and the coalition backing permanent daylight time is legislative and commercial rather than scientific. That is a real asymmetry, but it is science against commerce, not science against science.

The steady-state evidence, honestly graded

This is the argument that actually bears on standard-versus-daylight, and it is weaker than advocates usually let on. It rests on natural experiments at time-zone borders rather than on any trial of year-round daylight time, because no such trial has ever been run and measured properly.

• 19 minutesAn extra hour of evening natural light costs the average person 19 minutes of sleep a night, with knock-on effects on obesity, diabetes and income. This is the single best study in the debate — a clean discontinuity at time-zone borders, in a top field journal — and a western-edge location is functionally what permanent daylight time does to everyone.
• IRR 1.07Liver cancer incidence rises 7% per five degrees of longitude westward within a time zone, adjusted for shift work, income and health behaviours.
• No adjustmentEight weeks of actigraphy found sleep timing follows the seasonal progression of dawn under standard time, and does not under daylight time. The body clock does not adjust to the switch.
• 0.08 SDMoving a school start one hour later relative to sunrise raises maths scores by 0.08 standard deviations. Permanent daylight time moves every school start an hour earlier relative to sunrise.

The reason we started doing this stopped being true

Daylight saving time was an energy policy. It is worth being precise about how completely that rationale has collapsed, because the honest version is more damning than the myth.

The best meta-analysis in the field pooled 162 estimates from 44 studies and found a mean saving of 0.34% on days daylight time applies, with no publication bias. So the effect is real. It is also latitude-dependent, and it reverses in warm regions where air conditioning swamps lighting.

Indiana ran the cleanest natural experiment, because its counties adopted daylight time at different times. Seven million monthly billing observations later: residential demand went up about 1%, costing Indiana households $9 million a year. Australia's Olympic extension produced no reduction at all. The Department of Energy's own report to Congress found the 2007 extension saved 0.03% of annual national electricity.

The mechanism explains it. Lighting is about 6% of household electricity now. Air conditioning is 19% and heating is 12%. Daylight time trades a shrinking lever for a growing one, and LEDs shrink it further every year.

So do not say daylight saving time saves no energy. Say that the best pooled estimate is a third of a percent of electricity on the days it applies, that the cleanest natural experiments find zero or a loss, and that this cannot justify a nationwide intervention in when 340 million people wake up.