Europe's clocks go back on October 25; the United States follows a week later, on November 1. Either date triggers the same annual round of warnings. You have probably met the headline version by now: the twice-yearly clock change is bad for you, linked to heart attacks, to car crashes, to a measurable spike in harm in the days afterward. It is the kind of claim that sounds authoritative because it is half true. The half that goes missing is the half that matters this week.

Almost all of that alarm is about the other direction. The dangerous clock change, the one with the frightening numbers attached, is the spring one, the March morning when an hour is taken away. The change landing this month, October 25 in Europe and November 1 in the US, gives an hour back. They are not the same event, and reading them as if they were is how a real finding ends up describing the wrong week.

The costly transition is in spring

The asymmetry is not subtle once you look. A 2026 systematic review pulled together 157 studies across 36 countries and found that the spring transition, when the clocks jump forward and a night is shortened, correlates with more heart attacks and more fatal traffic accidents in the days that follow.[5] The autumn transition, the one that returns the hour, showed the opposite shape: it was associated with lower overall mortality and fewer workplace injuries, not more.[5]

That same split turned up in a very different place. A 2026 nationwide cohort study of more than twelve million people looked at new-onset retinal vascular disease, an outcome in the cardiovascular family, and again found elevated risk in the month after the spring change and reduced risk after the autumn one.[6] Two studies, two unrelated outcome classes, the same direction. The plausible mechanism behind the spring effect is the simple one: a stolen hour of sleep, groggier mornings, more drowsy driving before the body has caught up.[7]

None of that is the fall-back transition. It does not take the hour that does the damage. It hands one over.

What the fall-back change actually does

So what does gaining an hour do? On the evidence, remarkably little, at least to a generally healthy person. A 2026 study measured circadian and sleep biomarkers before and after a clock transition in healthy participants and found little if any effect on most of them.[8] A separate 2026 comparison of people living under daylight saving against people living under standard time found no meaningful difference in total sleep time or sleep onset, and no sign of impairment across the health measures they checked.[9] A third study, looking at dispensing rates for a common sedative, found a strong seasonal pattern but no change tied specifically to the clock transitions themselves.[10]

The honest read is not that nothing happens when the clocks move. It is that the dramatic figures belong to the spring direction and to the lost hour, and the gentle autumn version mostly does not reproduce them. If you feel a little scattered for a few days, the research does not say that feeling is imaginary. It says it is probably small, and probably not the thing the scary headline was counting.

Why the experts still want it gone

Here is the part that makes the mild version worth taking seriously anyway. Even though the autumn change looks benign, the scientific consensus is not that the clock change is fine. It is that the switching itself should stop. Three independent professional bodies have said so in formal position statements: the American Academy of Sleep Medicine,[2] the Sleep Research Society,[3] and the British Sleep Society,[4] joined this year by a Canadian health-policy analysis reaching the same place.[1] Their shared recommendation is worth getting right, because it cuts against the popular instinct: they favour permanent standard time, not permanent daylight saving.

That distinction matters. The appealing-sounding fix, locking the clocks onto permanent summer time so the evenings stay bright, is the one the sleep-medicine field specifically warns against, because it means darker mornings for months and a standing mismatch between the social clock and the sun.[1][2] So if you have ever felt faintly off after the clocks move and wondered whether you were making too much of it, the field that studies this for a living thinks the practice is enough of a problem to abolish. The feeling that a small thing is real is not the same as catastrophising it.

Two clocks moving at once

Part of why the autumn change is so easy to misread is that it never arrives alone. It lands right as the evenings are already drawing in, and those are two different machines. The clock change is an acute, one-night, externally-imposed jump. The darkening is the slow version, weeks of thinning light quietly loosening the rhythm that runs underneath mood, which is the story we told in the mood that tracks the light. You already know the smallest version of this from your own calendar, the way a few late weekend nights can leave Monday feeling shifted. The clock change is that same displacement, done to a whole country at once on a single Sunday.

The circadian system genuinely does sit close to the circuits that handle mood and sleep,[13][15] which is why a schedule shift is biologically plausible as something you might feel. What the research does not support is cleanly blaming this particular Sunday for a dip that the shortening season could explain just as well. When two things move together, neither one gets to take all the credit.

Where this lands

There is no technique at the bottom of this, no optimal way to spend the extra hour. The point is smaller, and it is mostly about accuracy. The clock change people warn about is in spring. This one gives the hour back, and for most people its direct cost is close to nothing the instruments can find. What is real is that it coincides with the season getting darker, and that the practice of switching at all is something the sleep-medicine field would rather end.

Holding a pattern like that across the years, so a dip in this stretch of autumn reads less like an isolated personal data point and more like a season a lot of people recognise, when the clock change and the darkening evenings arrive together, is part of what MoMo was built to hold. But that is a footnote. The argument is the correction: the frightening numbers are about March, and borrowing someone else's data point onto your own week is a quiet way to feel worse for no reason the evidence actually gives you.

If any of this lands in a heavy way, or if you are in distress or crisis, please reach out: Mind Sweden 90101 | Samaritans UK 116 123 | your local crisis line.

References

Lam, R. W., Mistlberger, R., Baylis, P., & Choi, A. (2026). Analysis of health impacts associated with adopting permanent standard time or permanent daylight saving time to inform policy in Canada. CMAJ, 198(34), E1335–E1340. PMID: 42833692. DOI: 10.1503/cmaj.261089.
Rishi, M. A., Cheng, J. Y., Strang, A. R., et al. (2024). Permanent standard time is the optimal choice for health and safety: an American Academy of Sleep Medicine position statement. Journal of Clinical Sleep Medicine, 20(1), 121–125. PMID: 37904574. DOI: 10.5664/jcsm.10898.
Malow, B. A. (2022). It is time to abolish the clock change and adopt permanent standard time in the United States: a Sleep Research Society position statement. Sleep, 45(12), zsac236. PMID: 36156090. DOI: 10.1093/sleep/zsac236.
Crawford, M. R., Winnebeck, E. C., von Schantz, M., et al. (2025). The British Sleep Society position statement on Daylight Saving Time in the UK. Journal of Sleep Research, 34(3), e14352. PMID: 39439274. DOI: 10.1111/jsr.14352.
Steponenaite, A., Wallraff, J. P., Wild, U., et al. (2026). A systematic review of epidemiological studies into daylight-saving time & health identifying beneficial & adverse effects. European Journal of Epidemiology, 41(4), 419–433. PMID: 41721993. DOI: 10.1007/s10654-026-01372-8.
Chan, K. S., Cheng, B. T., Banker, M. M., Zee, P. C., & Mirza, R. G. (2026). Daylight saving time transition and new-onset retinal vascular disease: a nationwide cohort study. Scientific Reports. PMID: 42362585. DOI: 10.1038/s41598-026-55281-7.
Assis, E. P., Silva, A. A. B., & Moreno, C. R. C. (2026). Influence of Seasonal and Chronobiological Factors on Driver Behavior and Traffic Accident Risk: A Scoping Review. Sleep Science, 19(1), 1–18. PMID: 42040901. DOI: 10.1055/s-0046-1819711.
Rea, M. S., Bullough, J. D., & Figueiro, M. G. (2026). Circadian Biomarkers Before and After the Transition to Spring Daylight Saving Time. Sleep Science, 19(2), 1–8. PMID: 42746665. DOI: 10.1055/s-0046-1824546.
Kemp, R. J., Adams, R. J., Haycock, J., & Lack, L. C. (2026). Are there lingering effects of Daylight-Saving Time on sleep and health estimates of an Australian population? Sleep Advances, 7(1), zpag009. PMID: 41891050. DOI: 10.1093/sleepadvances/zpag009.
Romaszko, M., Glińska-Lewczuk, K., Kocbach-Przudzik, A., & Majewski, M. (2026). Seasonal and daylight saving time-related variation in hydroxyzine prescribing. Chronobiology International, 43(10), 1642–1650. PMID: 42228613. DOI: 10.1080/07420528.2026.2682479.
Peripheral clocks and systemic zeitgeber interactions: from molecular mechanisms to circadian precision medicine (2025). Frontiers in Endocrinology. DOI: 10.3389/fendo.2025.1606242.
Rao, J. K., Emani, L. S., Padhi, S., Sharafkhaneh, A., Nami, M., & Rao, K. S. J. (2026). Sleep, emotional regulation, and limbic-cortical dynamics: From basic mechanisms to clinical translation. Progress in Brain Research, 299, 177–215. PMID: 42547207. DOI: 10.1016/bs.pbr.2026.07.002.