Daylight Saving Time and Health: Systematic Review with ☸️SAIMSARA.

DOI: 10.62487/saimsara13cb2638

Author: saimsara.com

Review Stats

Generated: 2025-10-28 09:55:00 CET
Plan: Premium (expanded craft tokens; source: Europe PMC)
Source: Europe PMC
Scope: All fields
Keyword Gate: Fuzzy (≥60% of required terms, minimum 2 terms matched in title/abstract)
Total Abstracts/Papers: 1777
Downloaded Abstracts/Papers: 1777
Included original Abstracts/Papers: 95
Total study participants (naïve ΣN): 1268808

Outcome-Sentiment Meta-Analysis (OSMA): (LLM-only)
Frame: Effect-of Predictor → Outcome • Source: Europe PMC
Outcome: health Typical timepoints: 50-y. Reported metrics: %, CI, p.
Common endpoints: Common endpoints: mortality, admission, complications.
Predictor: Daylight Saving Time — exposure/predictor. Typical comparator: standard time, the current policy in the us, those with a lower-fat diet, eastern partitions….

1) Beneficial for patients — health with Daylight Saving Time — [5], [15], [43], [68], [94] — ΣN=312472
2) Harmful for patients — health with Daylight Saving Time — [3], [7], [11], [16], [19], [20], [23], [24], [25], [27], [28], [31], [33], [35], [37], [41], [44], [46], [49], [50], [51], [52], [53], [56], [60], [61], [63], [64], [66], [71], [74], [77], [79], [81], [84], [88], [89], [90], [91], [95] — ΣN=775143
3) No clear effect — health with Daylight Saving Time — [1], [2], [4], [6], [8], [9], [10], [12], [13], [14], [17], [18], [21], [22], [26], [29], [30], [32], [34], [36], [38], [39], [40], [42], [45], [47], [48], [54], [55], [57], [58], [59], [62], [65], [67], [69], [70], [72], [73], [75], [76], [78], [80], [82], [83], [85], [86], [87], [92], [93] — ΣN=181193

1) Introduction
Daylight Saving Time (DST), a practice involving biannual clock shifts, has been pervasive in many societies for over 50 years, with governments increasingly considering its abandonment in favor of a single permanent time [21, 38]. The primary aim of DST, historically, was to improve conditions for indoor workers by regulating the private time of laboring classes [36]. However, the human circadian system is intrinsically linked to natural light-dark cycles, and arbitrary clock changes can induce internal desynchronization [41, 25]. This paper synthesizes recent epidemiological evidence to explore the multifaceted health effects of DST transitions and permanent DST or Standard Time (ST) policies, addressing both beneficial and adverse outcomes across various health domains.

2) Aim
This paper aims to systematically review and synthesize the available evidence on the health effects of Daylight Saving Time practices, identifying both beneficial and adverse impacts of transitions and living with DST compared to Standard Time, and to delineate key research gaps and clinical implications.

3) Methods
3.1 Eligibility criteria: Original studies investigating the health effects of Daylight Saving Time transitions or policies in human populations were included. This encompassed study designs such as randomized controlled trials (RCTs), cohort studies, mixed-methods studies, experimental studies, case-control studies, and cross-sectional analyses. Systematic reviews [1], editorials, conference papers, and studies not directly relevant to DST and health (e.g., mushroom identification [76]) were excluded. Studies involving animal populations were considered for contextual understanding of circadian disruption [13, 65].
3.2 Study selection: The studies included in this synthesis were identified through an upstream process utilizing a strict keyword gate related to "Daylight Saving Time and health," ensuring relevance to the query.
3.3 Risk of bias: The included studies exhibit a range of designs. Randomized controlled trials [2] offer strong evidence for causal inference, although only one was identified. Cohort studies [6, 8, 9, 11, 12, 17, 18, 19, 39, 40, 47, 49, 50, 51, 57, 61, 67, 72, 79, 80, 82, 83, 84, 85, 88, 89, 90, 91] provide insights into associations over time, but their susceptibility to confounding varies. Mixed-methods studies [1, 3, 4, 5, 7, 14, 15, 16, 20, 22, 23, 26, 27, 30, 31, 32, 33, 34, 35, 36, 37, 38, 41, 43, 44, 45, 46, 48, 53, 55, 56, 58, 59, 60, 62, 63, 64, 65, 68, 69, 70, 73, 74, 75, 77, 78, 81, 86, 87, 93, 95] often combine different approaches, but their specific methodologies and potential for bias were diverse. Several studies lacked specified sample sizes or follow-up periods, limiting the assessment of statistical power and long-term effects. Studies designated as "N/A" for study design [24, 25, 28, 29, 31, 35, 36, 46, 49, 54, 67, 70, 71, 74, 75, 89, 92, 94] or lacking specific directional type [1, 4, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 17, 18, 20, 21, 22, 23, 26, 27, 30, 31, 32, 34, 35, 36, 37, 38, 39, 41, 43, 44, 45, 46, 48, 49, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72, 73, 74, 75, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 93, 94, 95] presented challenges in fully evaluating their methodological rigor.
3.4 Synthesis: This paper was generated by an autonomous multilayer AI research agent (SAIMSARA) that performed keyword normalization, retrieval, structuring, and synthesis of research themes based solely on the provided structured extraction summary.

4) Results
4.1 Study characteristics: The included studies predominantly utilized mixed-methods, cohort, and cross-sectional designs, with one randomized controlled trial [2]. Populations varied widely, encompassing general human populations, specific adult cohorts (e.g., Australian adults, US adults, UK Biobank participants, Chinese healthcare professionals, European working population), students, drivers, and patients with specific conditions (e.g., acute myocardial infarction, suicidal thinking, diabetes). Animal studies on sled dogs and koalas were also present [13, 65]. Follow-up periods ranged from a few days or weeks around transitions to several years or decades, with many studies not specifying follow-up duration.
4.2 Main numerical result aligned to the query:
The spring Daylight Saving Time transition consistently resulted in a reduction of sleep duration. Across multiple studies, the median reported decrease in sleep duration on the DST transition Sunday or in the immediate aftermath was 50.07 minutes, with a range from 32 minutes to 65 minutes [12, 18, 66, 84, 90]. This acute sleep loss is a prominent and quantifiable health effect associated with the spring clock change.
4.3 Topic synthesis:

Sleep Disruption and Circadian Misalignment: Spring DST transitions are consistently associated with acute sleep loss (median 50.07 min, range 32-65 min) [12, 18, 66, 84, 90], decreased sleep efficiency [90], and increased daytime sleepiness [66]. This leads to internal desynchronization due to unsynchronized light exposure [41] and can enhance night-time restlessness [88]. Later chronotypes and individuals on high-fat diets may adapt more slowly [17, 40, 47, 86].
Cardiovascular Health Impacts: There is a suggestive association with minor increases in adverse cardiovascular events, such as acute myocardial infarction (AMI) (e.g., 27.2% increase in admissions [24], RR 1.04 [7], RR 1.039 [79], 3-4% increase in adverse events [16]), ischemic stroke hospitalizations (RR 1.08 [63]), and atrial fibrillation admissions (mean 3.09 vs 2.47 admissions/day [51]) following the spring DST transition. However, some studies found no significant changes in cardiovascular variables [22, 42].
Accidents and Safety Risks: Spring DST transitions are linked to increased risks of accidents, including a 51.58% increase in motorcyclist accidents [23, 33], a 6% increase in fatal motor vehicle accidents [50], and worsened driving performance and fatigue in young male drivers [27, 31, 52]. Conversely, DST in Chile was associated with a 2.7% reduction in automobile accidents [4], and overall road traffic fatalities and casualties showed minor reductions at both transitions in Great Britain [43].
Mental Health and Well-being: While some studies show reductions in anxiety, depression, and psychiatric conditions in the week after the Autumn clock change [5], others found no significant change in suicide rates [9]. However, later sunrise is associated with lower depression prevalence [93], and permanent Standard Time is favored for maximizing adequate morning light exposure [15, 59].
Work and Productivity: The spring DST transition can lead to decreased work engagement, especially for later chronotypes, partly due to lower sleep quality [20]. Workers may also sustain more workplace injuries and injuries of greater severity [84].
Policy and Public Perception: Exposure to DST-related health-risk messaging reduced DST policy support and increased perceived health consequences in Australian adults [2]. The majority of the EU's working population would benefit from eliminating DST if maximizing adequate morning light is the goal [15]. Public preferences for permanent time often vary, with a majority preferring to terminate clock adjustments [38].
Broader Health Outcomes and Social Effects: Modeling predicts decreases in obesity and stroke under permanent Standard Time or permanent DST compared to current policy, with biannual shifting producing a greater circadian burden [3]. DST transitions can also affect medical malpractice claims [11], reduce altruistic helping [46], and influence sedentary behavior [19].

5) Discussion
5.1 Principal finding: The most consistent and quantifiable health impact associated with Daylight Saving Time transitions is an acute reduction in sleep duration during the spring "spring forward" event, with a median decrease of 50.07 minutes (range 32-65 minutes) on the transition Sunday or immediate aftermath [12, 18, 66, 84, 90].
5.2 Clinical implications:

Increased Cardiovascular Risk: Clinicians should be aware of a potential transient increase in cardiovascular events, such as AMI and stroke, following the spring DST transition, particularly in susceptible populations like the elderly or those with underlying conditions [7, 24, 51, 63, 77, 79].
Sleep Hygiene Education: Public health campaigns could emphasize robust sleep hygiene practices in the week leading up to and immediately following the spring DST transition to mitigate acute sleep loss and associated daytime sleepiness [66, 90].
Occupational Safety Awareness: Employers, especially in industries with high-risk tasks, should consider the increased risk of workplace injuries and driving fatigue in the days following the spring DST change [27, 31, 52, 84].
Mental Health Monitoring: While direct links to suicide rates are not consistently found [9], the impact of circadian disruption on mental health warrants attention, particularly for individuals with existing psychiatric conditions [5].
Chronic Disease Management: Patients with conditions sensitive to circadian disruption, such as diabetes requiring insulin pumps, should be advised on careful adjustment of medical devices during clock changes [75].

5.3 Research implications / key gaps:

Longitudinal Circadian Impact: Future studies should prospectively assess the long-term effects of permanent DST versus permanent Standard Time on human circadian rhythmicity and health outcomes using objective measures of light exposure and sleep timing [14, 41].
Vulnerable Population Studies: Research is needed to identify specific subgroups (e.g., chronotypes, individuals with pre-existing conditions, different age groups) that are most susceptible to adverse health effects from DST transitions or specific time policies [17, 40, 47, 63, 77, 86, 91].
Economic and Societal Burden: Studies should quantify the full economic and societal costs associated with DST-related health detriments, including healthcare utilization, productivity losses, and accident-related expenses, to inform policy decisions [11, 24, 46].
Intervention Efficacy: Randomized controlled trials or quasi-experimental designs could evaluate the effectiveness of interventions (e.g., targeted light therapy, behavioral adjustments) in ameliorating the negative health impacts of DST transitions [41].
Policy Impact Modeling: Further sophisticated modeling is required to predict the comprehensive health benefits or detriments of different permanent time policies (Standard Time vs. DST) across diverse geographical regions and populations [3].

5.4 Limitations:

Heterogeneity of Outcomes — The studies report a wide array of health outcomes with varied metrics, making direct quantitative synthesis challenging for many areas beyond sleep duration.
Lack of Causal Inference — Many studies are observational (cohort, mixed-methods) rather than interventional, limiting the ability to establish definitive causal relationships between DST and health outcomes.
Population Specificity — Findings are often specific to particular populations (e.g., high school students, Australian adults, specific regions), limiting generalizability to broader global populations.
Incomplete Data Reporting — Several summaries lacked specific sample sizes, follow-up durations, or detailed statistical reporting, hindering a comprehensive assessment of study quality and impact.
Focus on Transitions — The majority of research focuses on the acute effects of clock changes, with less emphasis on the chronic health implications of living under a permanent DST or ST regime.

5.5 Future directions:

Standardized Outcome Metrics — Develop and implement standardized health outcome metrics for DST research to enable more robust meta-analyses.
Longitudinal Cohort Studies — Conduct large-scale, long-term cohort studies tracking health markers across multiple DST transitions and policy changes.
Objective Sleep Monitoring — Utilize wearable technology for objective, continuous sleep and activity monitoring in diverse populations around DST changes.
Policy Intervention Trials — Design and execute quasi-experimental studies to evaluate the health impacts of regions adopting permanent Standard Time or DST.
Public Health Messaging — Evaluate the effectiveness of targeted public health campaigns aimed at mitigating adverse health effects of DST transitions.

6) Conclusion
The most consistent and quantifiable health impact associated with Daylight Saving Time transitions is an acute reduction in sleep duration during the spring "spring forward" event, with a median decrease of 50.07 minutes (range 32-65 minutes) on the transition Sunday or immediate aftermath [12, 18, 66, 84, 90]. While this acute sleep loss is well-documented across various human populations, the generalizability of other health effects, such as cardiovascular risks and accident rates, is limited by the heterogeneity of study designs, populations, and reported outcomes. The primary limitation affecting the certainty of broader health impacts is the Heterogeneity of Outcomes, which impedes direct comparisons and robust synthesis. A concrete next study involves conducting large-scale, longitudinal cohort studies with objective health monitoring to definitively assess the long-term health implications of permanent Standard Time versus permanent Daylight Saving Time.

References
SAIMSARA Session Index — session.json

Figure 1. Publication-year distribution of included originals

Figure 1. Publication-year distribution of included originals

Figure 2. Study-design distribution of included originals

Figure 2. Study-design distribution

Figure 3. Study-type (directionality) distribution of included originals
Figure 3. Directionality distribution

Figure 3. Directionality distribution

Figure 4. Main extracted research topics

Figure 4. Main extracted research topics (Results)

Figure 5. Limitations of current studies (topics)

Figure 5. Limitations of current studies (topics)

Figure 6. Future research directions (topics)

Figure 6. Future research directions (topics)