Why would moving the clock an hour change anyone's health?
The idea is that shifting the clock by an hour creates a small, abrupt disruption to sleep and daily rhythm, sometimes described as a "mini-jetlag" [5]. Because the spring and autumn changes push the body in opposite directions, the effects need not be symmetrical: one transition may cost sleep and add stress, while the other may allow a little more rest.
That asymmetry is the key to the question. If spring changes squeeze sleep and autumn changes relax it, we would expect harms concentrated in spring and possible benefits in autumn, rather than a single uniform "daylight saving is bad" effect. The 2026 review explicitly tested this framing and concluded that the messaging of transitions being uniformly detrimental is not supported [3].
Heart attacks, deaths, and accidents do not all move the same way
For heart attacks, the signal is concentrated in spring. The systematic review found that DST-onset transitions appear associated with increased acute myocardial infarction [3]. That is a specific, time-limited risk around the spring change, not a claim that heart attacks are generally higher throughout the whole daylight-saving period.
For deaths and workplace accidents, the pattern runs the other way. The same review found that DST-offset transitions, the autumn change, appear associated with decreased all-cause mortality and decreased workplace accidents [3]. It also found that living with daylight saving during summer, compared with standard time, appears associated with lower all-cause mortality and fewer traffic accidents in summer [3].
Traffic accidents complicate the picture, because the direction depends on which transition you look at. The review reports that spring transitions appear associated with increased fatal traffic accidents, while summer daylight saving appears associated with fewer traffic accidents overall [3]. So "accidents" is not one outcome: fatal road crashes and workplace accidents can move in different directions at different points in the year.
How firm is this pattern?
The review itself is cautious. It drew on 157 studies of varying designs and quality from 36 countries, and it describes the evidence base as limited and heterogeneous [3]. Its language is "appear associated" rather than "caused by," which matters: these are observational patterns around a calendar event, not controlled experiments in which people are randomly assigned to change the clock or not.
Some of the surrounding literature is less directly useful than it first appears. One widely cited line of work on daylight saving and health examines US and German data and reports asymmetric health impacts between spring and fall changes, but it does not specifically measure death rates, workplace accidents, or heart attacks [1]. Another study on the same theme reports changes in self-reported health and hospital admissions but likewise does not directly measure those three outcomes [5]. Studies linking heart rate or social ties to mortality and coronary heart disease are about long-term risk factors, not about clock changes, so they cannot confirm or refute a short-term transition effect [2][4].
So is the answer yes?
Broadly, yes, with the emphasis on "appears." The most direct synthesis supports the shape of the question: spring changes are linked to more acute heart attacks and more fatal traffic crashes, while autumn changes are linked to lower all-cause mortality and fewer workplace accidents [3]. That is a coherent and somewhat surprising combination, and it fits the idea that the two transitions are not mirror images of each other.
What the evidence does not support is a blanket verdict that clock changes are simply harmful or simply helpful. The review found no clear and consistent effects on psychiatric outcomes, and limited studies prevented firm conclusions on other sleep and circadian measures [3]. Its recommendation is therefore balanced: recognize both the adverse and beneficial patterns, and focus on mitigating risks while stronger evidence accumulates [3].
Sources used in this answer
Does daylight saving time really make us sick?
Examines US and German data and reports asymmetric health impacts between spring and fall clock changes, but does not specifically address death rates, workplace accidents, or heart attacks.
Heart rate as a prognostic factor for coronary heart disease and mortality: findings in three Chicago epidemiologic studies
Investigates heart rate as a prognostic factor for coronary heart disease and mortality across three Chicago epidemiologic studies, without any connection to daylight saving time.
A systematic review of epidemiological studies into daylight-saving time & health identifying beneficial & adverse effects.
A systematic review of 157 studies from 36 countries finds spring transitions associated with increased acute myocardial infarction and fatal traffic accidents, and autumn transitions associated with decreased all-cause mortality and workplace accidents.
Social ties and change in social ties in relation to subsequent total and cause-specific mortality and coronary heart disease incidence in men
Examines social ties in relation to mortality and coronary heart disease incidence in men, with no bearing on daylight saving time transitions.
Sleep and human capital: Evidence from daylight saving time
Analyzes daylight saving time effects on sleep and health outcomes such as self-reported health and hospital admissions in the US and Germany, without directly measuring death rates, workplace accidents, or heart attacks.