Daylight Saving Time and Sleep: Why Losing One Hour Hits So Hard

Written by the Nuvirox Research Team

Short answer: it’s a small clock change with a genuinely outsized biological cost, and most of that cost is avoidable with a few days of preparation. Losing just one hour in the spring "spring forward" transition sounds trivial, but a growing body of research links it to measurable sleep loss, mood disturbance, and even short-term shifts in accident and mortality patterns — enough that major sleep medicine organizations have taken a formal public position against continuing the practice.

Why does losing one hour matter so much?

The spring transition doesn't just cost you an hour of sleep opportunity that one night — it also misaligns your circadian clock with the new, earlier-than-your-body-expects wake time, similar in kind (if smaller in magnitude) to jet lag. Because standard time is more closely aligned with the sun's actual position, the spring shift to daylight saving time pushes your social schedule further from your biological rhythm, particularly affecting evening chronotypes and anyone with early fixed start times.

What does the research actually document?

Direct sleep loss. One frequently cited analysis found the average person gets about 40 minutes less sleep on the Monday following the spring transition. A separate study of teenagers specifically found an average loss of 32 minutes of sleep per night after the change, totaling nearly 2 hours and 42 minutes of cumulative lost sleep across the following week, with measurable next-day effects including slower reaction times and more difficulty paying attention in school.

A 2025 systematic review pooling 27 studies found the transition to DST was consistently associated with worse sleep duration and quality, and increased daytime sleepiness, with effects more pronounced in evening chronotypes — adding weight to the idea that this isn't a uniform burden across everyone, but hits some people meaningfully harder.

Mortality and accident data. A study examining all-cause mortality across 16 European countries from 1998 to 2012 found mortality patterns shifted measurably in the two weeks following each DST transition — decreasing in spring and increasing in fall — alongside a broader weekly pattern of lowest mortality on Sundays and highest on Mondays that persisted around the transitions. Separate research has found the spring transition is associated with an increased risk of fatal traffic accidents, cited at around a 6% rise in one analysis, alongside documented increases in heart attack and stroke risk in the days immediately following the change.

The honest counterweight. The fall "fall back" transition, which gives an extra hour, is generally less disruptive for most people and can even feel like a brief reprieve — though some people still have difficulty adjusting to the new, earlier-feeling wake-up time. Not every study finds identical effect sizes, and much of the mortality and accident research is observational (population-level patterns) rather than showing individual causation, which is worth keeping in mind even as the overall direction of evidence looks consistent.

What actually helps blunt the effect

• Shift your bedtime and wake time by 15–20 minutes earlier for a few nights before the spring transition, rather than absorbing the full hour-shift all at once — this is the AASM's specific recommendation.
• Prioritize getting a full night's sleep in the days immediately before and after the change, since baseline sleep debt makes the transition harder to absorb.
• Get morning light exposure on the days following the change to help re-anchor your circadian clock to the new schedule.
• Be extra cautious driving in the days right after the spring change, given the documented uptick in accident risk during that window.

Frequently asked questions

Is the spring or fall time change worse for sleep?

The spring "spring forward" transition, which removes an hour, is consistently documented as more disruptive than the fall transition, which adds an hour back. Research on sleep loss, mood disturbance, and accident risk is concentrated around the spring change.

How long does it take to adjust after daylight saving time starts?

For most people, the acute effects fade within a few days to a couple of weeks, though a systematic review found the disruption is more pronounced and possibly longer-lasting in evening chronotypes.

Is there a real medical case for ending daylight saving time?

The American Academy of Sleep Medicine has formally taken the position that seasonal time changes should be eliminated in favor of permanent standard time, citing evidence on medical errors, accidents, and hospital admissions linked to the transitions. This remains a live policy debate rather than a settled matter.

From Nuvirox

Why we formulated Sleep+ Restore

The week around a clock change is exactly when a consistent bedtime cue is most useful. Sleep+ Restore’s 10 mg melatonin and calming botanical blend can support the gradual bedtime shift the AASM recommends in the days before and after daylight saving time begins.

Learn more about Sleep+ Restore →

The bottom line

A one-hour clock change sounds minor, but the research on sleep loss, mood disturbance, and accident risk around the spring transition is consistent enough that sleep medicine's leading professional organization has formally called for ending the practice. Gradually shifting your schedule in the days before the change, rather than absorbing the full hour at once, is the most evidence-backed way to blunt the impact.

Does the fall time change cause any problems too?

Generally less than the spring change, since gaining an hour is easier for the body to absorb than losing one. However, some people, particularly those who are already early risers, find the fall change makes them wake up even earlier relative to the clock, and there's some research suggesting mood-related effects (including a documented seasonal pattern in mood disorders) that cluster loosely around the shorter-daylight months the fall change also coincides with, though separating the clock-change effect from the broader seasonal daylight reduction is difficult in that specific case.

Are children affected differently by the time change than adults?

Children, and teenagers in particular, are frequently cited in the research as experiencing more pronounced sleep loss and next-day impairment after the spring transition, partly because school start times don't shift and partly because adolescent circadian rhythms are already naturally shifted later, making an earlier forced wake time especially disruptive. The gradual-adjustment strategy recommended for adults is generally recommended for children as well, sometimes started even earlier given how sensitive this age group appears to be.

Does exposure to morning light really speed up adjustment?

Light remains the primary input the circadian clock uses to reset itself, so morning light exposure in the days following a clock change is a mechanistically sound recommendation, consistent with how light-based circadian adjustment works for jet lag and shift work more broadly, even though it hasn't been isolated as its own variable in a dedicated DST-specific trial.

References

1. The effects of daylight saving time and clock time transitions on sleep and sleepiness: a systematic review. Sleep Med Rev. 2025.
2. Sleep experts want to stop 'springing forward' to daylight saving time. American Academy of Sleep Medicine, 2023.
3. Daylight saving time affects European mortality patterns. PMCID: PMC9659560.
4. Daylight Saving Time: Everything You Need to Know. Sleep Foundation overview.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.