The window slides. It never grows.
Daylight saving time is named after something that does not happen. On the shortest day in Chicago there are nine hours and eight minutes of daylight. No clock setting makes it nine and a half.
Moving the clock forward moves the window later. It does not lengthen it. So the real question was never how much light we get. It is which end of the day we hand it to.
Permanent daylight saving time takes an hour off every winter morning and gives it to the evening. That is the entire transaction, and it is worth arguing about honestly. But it should be argued about as what it is: a transfer, not a gain.
Pick a city below, then switch regimes. Watch the sunrise move. Watch the sunset move. Watch the daylight total refuse to budge.
Sunrise and sunset computed with the NOAA solar algorithm and checked against the US Naval Observatory. Early January is used because the year's latest sunrise falls a fortnight after the solstice, not on it.
That locked number is the argument. Everything else on this site is a fight over who should get the hour we already have.
The solar position algorithm behind every time on this site.
gml.noaa.gov/grad/solcalc/
Every computed sunrise here was checked against the Naval Observatory and matched within one minute.
aa.usno.navy.mil/data/RS_OneYear
There are two questions here, and almost everyone blurs them.
- Should we stop changing the clocks twice a year? Nearly everyone says yes. Between 61% and 72% in every recent poll, whichever pollster asks. The harms at the transitions are real and modest: roughly 4–6% more heart attacks and fatal crashes in the days after we spring forward, and no measurable effect in the fall.
- If we stop, which time do we stop on? This is where the actual disagreement lives, and the transition evidence has nothing to say about it. Stopping on standard time removes the switch. Stopping on daylight time removes the switch. Both fix the first problem.
Blurring these two is how a bill that does the opposite of what every sleep-science body recommends passed the House with 308 votes. "End the clock change" polls at two thirds. "Permanent daylight saving time" is what got written into the bill.
What this site refuses to do
Most of the loudest statistics in this debate are about the switch. We do not use them to argue about which time to land on, because they cannot carry that weight. The case for standard time has to stand on its own evidence, and we say plainly where that evidence is thinner.
Pooled RR 1.04 (95% CI 1.02–1.07) for heart attacks after the spring transition; the autumn transition is not significant.
pubmed.ncbi.nlm.nih.gov/38888468/
732,835 fatal crashes over 22 years: +6% after spring forward, worse in the morning and worse the further west you sit in your time zone. No effect in the fall.
pubmed.ncbi.nlm.nih.gov/32008905/
U.S. House of Representatives, Roll Call 238 — H.R. 139, Sunshine Protection Act, On Passage, 14 July 2026, 5:17 PM. Passed 308–117.
clerk.house.gov/evs/2026/roll238.xml
Our conclusion, in short
Stop switching. The twice-yearly change buys nothing anybody can measure and costs a week of real harm each spring. That part is close to settled.
Then land on standard time. Not because the health evidence is overwhelming — it is suggestive, contested in places, and we lay out the contest. Because of three things that are harder to argue with: no scientific body anywhere endorses permanent daylight time, standard time is the setting that matches the sun, and permanent daylight time is the one option we have already tried four times in four countries and abandoned every time.
The full reasoning, including the strongest version of the case against us, is on the pages that follow.
Next Your winter sunrise What permanent daylight saving time would do to the morning where you live.More than twenty medical, scientific and civic organizations back permanent standard time. Not one scientific body backs permanent daylight time.
sleepresearchsociety.org/wp-content/uploads/20…