Forward this to a friend who sleeps badly.

The clocks get an extra hour. Your body clock did not sign off on it.

In less than two weeks, on Sunday, Nov. 1, most of the country sets the clocks back one hour at 2 a.m. local time. Much of Arizona skips the whole ritual and stays on standard time all year.

The bigger question comes back every spring and fall: what if we stopped switching? A 2025 study tried to answer it with a computer model of the human body clock.

This is a look-back at a paper from September 2025, not a new breakthrough. It also measured no one. The news peg is the calendar, not the study.

Researchers at Stanford simulated a full year of daylight and indoor light for counties across the contiguous US under three policies: the current twice-a-year switch, permanent standard time, and permanent daylight saving time. Then they ran that light through a mathematical model of the circadian clock.

In the model, switching twice a year put more strain on the body clock than either permanent option. The authors call this strain "circadian burden": the total amount the internal clock has to shift over a year to stay in sync with the outside world.

The team linked the model results to CDC county health data and adjusted for health and socioeconomic factors. Compared with today's policy, the model predicted slightly lower obesity and stroke prevalence under both permanent options, with permanent standard time a little further ahead.

One important update: in April 2026, PNAS published a correction from the authors about a coding error in the light simulation that, they say, affected all models and time policies. The notice does not say whether the published numbers changed, so we are leaving out the exact estimates until that is clear. PNAS also ran two critical letters, one questioning the county-level design and one questioning the strain measure, plus a reply from the authors, who agree the work does not show cause and effect for individuals.

For arthritis, cancer, coronary heart disease, COPD, depression, and diabetes, the predicted changes were small and not statistically significant.

"Predicted" is doing a lot of work in that last section. Nobody was moved to a new time policy, weighed, or followed for years. The study is a simulation.

Here is the world the model assumed. Everyone slept from 10 p.m. to 7 a.m., every day, in the dark. Everyone worked 9 to 5, Monday through Friday, in a "well-lit office" (500 lux). Once the sun got dimmer than indoor lighting, evenings meant 120 lux of indoor light until bedtime. Mornings, after work, and weekends came with sunlight. The authors chose this schedule to represent the smallest possible strain on the body clock.

The model also used three body-clock types: early, intermediate, and late, set as internal days of 24.0, 24.2, and 24.4 hours. The health predictions used the intermediate type only.

Then came the health part. The county data came from the CDC PLACES dataset, which is self-reported and summarized by county, not tracked person by person. The authors write that their estimates "are predictive rather than causal." In plain English: if the assumptions hold, this is their best guess. It is not proof that a time policy causes or prevents obesity or stroke.

One more boundary. The study looked at long-term, year-round effects. It did not test what happens in the days right after the clocks change.

The claim: pressing certain spots on your ear helps you fall asleep faster or sleep better.

What was studied: The newest review (Luo and colleagues, Medicine, 2026) pooled 25 randomized trials with 2,106 people with primary insomnia. Some trials compared ear methods with a sleeping pill. Only 8 of the 25 had a sham (fake treatment) control, and 3 of those tested real ear acupressure. The authors say their results still need to be confirmed.

How good is the evidence? Only 7 of the 25 trials were blinded, and 24 of the 25 were run in China. An older review (Lan and colleagues, 2015, a look-back) pooled 15 trials with 1,429 participants, 14 of them from China, Hong Kong, or Taiwan, and rated the evidence as low quality.

Harm? Only 6 of the 25 trials in the 2026 review recorded side effects at all. The ones reported were mild: skin irritation from the patches, one hematoma, and pain from an ear clip.

The better-supported first step: cognitive behavioral therapy for insomnia (CBT-I). The American College of Physicians (2016) recommends it as the initial treatment for chronic insomnia in adults, and the American Academy of Sleep Medicine (2021) gives it a strong recommendation. The ACP guideline rated the evidence for acupuncture as insufficient.

Verdict: Low risk, weak evidence. Ear acupressure looks low-risk and some small trials report better sleep scores, but the studies are mostly small, rarely well blinded, and at high risk of bias, so it's not a proven insomnia treatment and not a substitute for CBT-I.

Real life rarely runs on the model's schedule, and the authors say so themselves. In reality, they write, people "may have highly erratic sleep schedules," "spend much of their time indoors," and shift their sleep timing a lot between workdays and days off. The model also did not account for seasonal changes in behavior, like less time outside in winter.

One clock policy does not fit every body either. How far north you live, where you sit inside your time zone, and your chronotype all changed the results. In the original analysis, comparing the two permanent options, standard time meant less strain in most counties for intermediate and late types. For early types it flipped, and permanent daylight time meant less strain in most counties. Those county results come from the same model the correction covers.

That is a model detail, not a ruling for your household. It does give early birds and night owls one more thing to politely disagree about.

A related look-back, since the model assumed perfectly regular sleep: in a 2024 UK Biobank study of 60,977 middle-aged and older adults who wore a wrist device for about a week, the most regular fifth of sleepers had a lower risk of death over about six years than the least regular fifth (hazard ratio 0.70 after full adjustment). That is an association in a UK sample, not proof that a steady schedule extends life. The authors note regularity may be both a cause and a marker of health.

If the clocks stopped changing for good, which would you keep?

A. Permanent standard time.
B. Permanent daylight saving time.

Reply with A or B. This is a conversation starter, not a scientific survey. "Whichever one gives me the extra hour" is, sadly, not on the ballot.

Weed L, Zeitzer JM (2025). Circadian-informed modeling predicts regional variation in obesity and stroke outcomes under different permanent US time policies. PNAS 122(38): e2508293122. Published Sept. 15, 2025 (look-back). https://doi.org/10.1073/pnas.2508293122 Free full text: https://pmc.ncbi.nlm.nih.gov/articles/PMC12478180/ Modeling study; the authors describe their estimates as predictive rather than causal. Example code: https://github.com/Lara-Weed/CircadianTimePolicy Correction: PNAS 123(18): e2612351123 (April 2026). https://doi.org/10.1073/pnas.2612351123 Letters: PNAS 123(17): Erren et al., e2527389123; Martín-Olalla and Mira, e2532075123; authors' reply, e2533444123 (PNAS, April 2026).

Research transparency: funded by the NIH National Heart, Lung, and Blood Institute (F31HL170715). The authors declare no competing interest.

Luo Z, Shen J, Chen X, Zhang Q, Xiong J (2026). Efficacy of auriculotherapies for primary insomnia: a systematic review and network meta-analysis. Medicine (Baltimore) 105: e48357. https://doi.org/10.1097/md.0000000000048357 Funding: Chongqing Three Gorges Medical College and Chongqing Municipal Education Commission; the authors report no conflicts of interest.

Lan Y et al. (2015, look-back). Auricular acupuncture with seed or pellet attachments for primary insomnia: a systematic review and meta-analysis. BMC Complementary and Alternative Medicine 15: 103. https://doi.org/10.1186/s12906-015-0606-7

Qaseem A et al. (2016). Management of chronic insomnia disorder in adults: a clinical practice guideline from the American College of Physicians. Annals of Internal Medicine 165(2): 125-133. https://doi.org/10.7326/M15-2175

Edinger JD et al. (2021). Behavioral and psychological treatments for chronic insomnia disorder in adults: an American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine 17(2): 255-262. https://doi.org/10.5664/jcsm.8986

Windred DP, Burns AC, Lane JM, et al. (2024, look-back). Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study. SLEEP. https://doi.org/10.1093/sleep/zsad253 Observational study. Two authors (Phillips and Cain) report research funding from Delos and Versalux and co-founded Circadian Health Innovations; Cain also reports research funding from Beacon Lighting and consulting for Dyson.

Your Better Mind: a newsletter from the Toronto-based forBetterMinds team that turns brain-health research into everyday habits, with careful notes on what each study did and didn't measure. Their "Sleep and Brain Health" issue is a great place to start. Subscribe free: https://forbetterminds.beehiiv.com/

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The Sleep News provides general information, not personal medical advice. If sleep problems persist or affect safety, seek qualified medical care.

Forward this to a friend who sleeps badly.