Daylight-Saving Time & Health: A Systematic Review of Beneficial & Adverse Effects

OBJECTIVETo systematically review and narratively synthesize the epidemiological evidence regarding health effects of Daylight-Saving Time (DST) practices. METHODSO_ST_ABSEligibility CriteriaC_ST_ABSPeer-reviewed, primary research of humans published in English or German and that assessed either (i) health effects of transitions (we allowed up to one month as the index period), or (ii) health differences between living with DST vs Standard Time at a given time of year, or (iii) or health effects of living at the same latitude but different longitude within the same time zone were included. Eligible health effects were broadly categorised as all-cause mortality, accident (traffic/workplace/home/substance-related)-, cardiovascular-, gastrointestinal, immunologic-, psychiatric-, neurologic-, circadian and sleep-, and cognitive-related outcomes, as well as healthcare appointments/admissions. Adverse and beneficial effects were included. Information SourcesPubMed, Web of Science Core Collection, Scopus, PsychINFO, and EconLit were systematically searched in March 2023 and then updated to June 2025. Synthesis OrganisationStudies were organised by outcomes into the following categories: (1) cardiovascular, (2) psychiatric, (3) traffic accidents, (4) non-traffic accidents (e.g., workplace), (5) sleep and circadian, (6) cognitive, and (7) neurological and gastrointestinal and all-cause mortality, and narratively synthesised by at least two authors. Some studies were included under multiple categories. Synthesis conclusions were based on quality and quantity of studies. Next, a synthesis of the syntheses was written and confidence in validity of outcomes was illustrated with agreement from all authors. The authorship team included expertise in sleep and chronobiology with additional expertise in physiology, psychiatry, neuroscience, and epidemiology. Risk of Bias AssessmentCritical appraisal was independently conducted by at least two authors using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies, with studies categorized as low, medium, or high quality. Narrative syntheses of studies identified additional strengths and limitations. RESULTSO_ST_ABSIncluded ResultsC_ST_ABSN=157 studies of diverse designs and varying quality from 36 different countries were identified. Exact participant numbers cannot be determined as many studies utilised nationwide databases/registries or included DST-associated assessments as either secondary objectives or as one part of a main objective (e.g., sleep assessment across a year). Nonetheless, the participant pool can be considered substantial. SynthesisDST-Onset transitions appear associated with increased acute myocardial infarction (17 studies, 6 high quality) and fatal traffic accidents (16 studies, 4 high quality) but decreased crimes involving physical harm (5 studies, 3 high quality). DST-Offset transitions appear associated with decreased all-cause mortality (3 studies, 1 high quality) and workplace accidents (8 studies, 2 high quality), but increased crimes involving physical harm. Living with DST (as opposed to Standard Time) is associated with decreased all-cause mortality and traffic accidents in summer, the latter only tested during initial months (2 high quality studies), and possibly sleep duration during winter (2 low quality studies). No studies identify clear effects on psychiatric outcomes (15 studies, 1 high quality). Apart from DST-Offset associations with increased sleep duration (22 studies, 2 high quality), limited studies prevent clear conclusions being drawn regarding sleep duration for other periods or regarding the timing of sleep onset and offset or regarding circadian rhythm disruptions (6 studies, 0 high quality). CONCLUSIONSWhat this review shows (including outcome-specific detrimental effects, null effects, and beneficial effects of transitions and of living with DST compared to Standard Time during summer months) is that the evidence does not support the messaging of transitions and DST during summer months being uniformly detrimental. The potential benefits of DST during summer on mortality and traffic accidents and of DST-Offset transitions on sleep, mortality, and work place accidents present an argument for maintaining transitions (from a health perspective) and for identifying mitigation strategies against adverse effects, at least for now, until further research suggests otherwise. REGISTRATIONhttps://doi.org/10.17605/OSF.IO/R4W6M