Accident rates and the impact of daylight saving time transitions

The Annual Rhythms in Sleep, Sedentary Behavior, and Physical Activity of Australian Adults: A Prospective Cohort Study

BACKGROUND

Sleep, sedentary behavior, and physical activity have fundamental impacts on health and well-being. Little is known about how these behaviors vary across the year.

PURPOSE

To investigate how movement-related behaviors change across days of the week and seasons, and describe movement patterns across a full year and around specific temporal events.

METHODS

This cohort study included 368 adults (mean age = 40.2 years [SD = 5.9]) who wore Fitbit activity trackers for 12 months to collect minute-by-minute data on sleep, sedentary behavior, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Data were analyzed descriptively, as well as through multilevel mixed-effects linear regression to explore associations with specific temporal cycles (day-of-the-week, season) and events.

RESULTS

Movement patterns varied significantly by day-of-the-week and season, as well as during annual events like Christmas-New Year and daylight saving time (DST) transitions. For example, sleep was longer on weekends (+32 min/day), during autumn and winter relative to summer (+4 and +11 min/day), and over Christmas-New Year (+24 min/day). Sedentary behavior was longer on weekdays, during winter, after Christmas-New Year, and after DST ended (+45, +7, +12, and +8 min/day, respectively). LPA was shorter in autumn, winter, and during and after Christmas-New Year (-6, -15, -17, and -31 min/day, respectively). Finally, there was less MVPA on weekdays and during winter (-5 min/day and -2 min/day, respectively).

CONCLUSIONS

Across the year, there were notable variations in movement behaviors. Identifying high-risk periods for unfavorable behavior changes may inform time-targeted interventions and health messaging.

Permanent standard time is the optimal choice for health and safety: an American Academy of Sleep Medicine position statement

The period of the year from spring to fall, when clocks in most parts of the United States are set one hour ahead of standard time, is called daylight saving time, and its beginning and ending dates and times are set by federal law. The human biological clock is regulated by the timing of light and darkness, which then dictates sleep and wake rhythms. In daily life, the timing of exposure to light is generally linked to the social clock. When the solar clock is misaligned with the social clock, desynchronization occurs between the internal circadian rhythm and the social clock. The yearly change between standard time and daylight saving time introduces this misalignment, which has been associated with risks to physical and mental health and safety, as well as risks to public health. In 2020, the American Academy of Sleep Medicine (AASM) published a position statement advocating for the elimination of seasonal time changes, suggesting that evidence best supports the adoption of year-round standard time. This updated statement cites new evidence and support for permanent standard time. It is the position of the AASM that the United States should eliminate seasonal time changes in favor of permanent standard time, which aligns best with human circadian biology. Evidence supports the distinct benefits of standard time for health and safety, while also underscoring the potential harms that result from seasonal time changes to and from daylight saving time.

CITATION

Rishi MA, Cheng JY, Strang AR, et al. Permanent standard time is the optimal choice for health and safety: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2024;20(1):121-125.

The Effects of Daylight Saving Time (DST) Transition Cancelation on Work Accidents of Turkey

Objectives. Turkey canceled the daylight saving time (DST) transition and started permanent clock application. Considering the effect of this new regulation on working hours, this study examines whether there is a relationship with the increase in the number of work accidents in shifts. Methods. Data on work accidents were obtained from the Republic of Turkey Social Security Institution (SSI), filed between 2011 and 2020. We estimate accident rates using Poisson regression and log-linear models as a function of a variety of date-based factors. Results. The results show that DST transition is effective (ineffective in terms of gender) on changes in the number of work accidents. With statistical analyses, the hourly distribution of work accidents was determined, indicating at which hour the most work accidents occurred, using the work accident frequency rate. The number of prevented work accidents was calculated as 286,793 for Turkey. Conclusion. The findings from these studies suggest that cancellation of the DST transition does not have a negative effect on the incidence of work accidents in Turkey; on the contrary, this practice also serves the purpose of preventing work accidents.

Driving fatigue increases after the Spring transition to Daylight Saving Time in young male drivers: A pilot study

The Spring transition to Daylight Saving Time (DST) has been associated with several health and road safety issues. Previous literature has focused primarily on the analysis of historical crash and hospitalization data, without investigating specific crash contributing factors, such as driving fatigue. The present study aims to uncover the effects of DST-related circadian desynchrony and sleep deprivation on driving fatigue, by means of a driving simulator experiment. Eighteen participants (all males, age range 21-30 years, mean = 24.2, SD = 2.9) completed two 50-minute trials (at one week distance, same time and same day of the week) on a monotonous highway environment, the second one taking place in the week after the Spring transition to DST. Driving fatigue was evaluated by analysing several different variables (including driving-based, physiological and subjective indices) and by comparison with a historical cohort of pertinent, matched controls who had also undergone two trials, but in the absence of any time change in between. Results showed a considerable rise in fatigue levels throughout the driving task in both trials, but with significantly poorer performance in the post-DST trial, documented by a worsening in vehicle lateral control and an increase in eyelid closure. However, participants seemed unable to perceive this decrease in their alertness, which most likely prevented them from implementing fatigue-coping strategies. These findings indicate that DST has a detrimental effect on driving fatigue in young male drivers in the week after the Spring transition, and provide valuable insights into the complex relationship between DST and road safety.

Using text mining and multilevel association rules to process and analyze incident reports in China

Incident investigation reports provide information on defects related to the system safety and indications for improvements. Currently, the analysis of these reports relies heavily on expert' experience. The foreseeable work-load and lack of understanding about the importance of near misses have created a situation where severe accidents are rigorously investigated, and minor incidents are often omitted. Consequently, incident reports have not been fully analyzed to provide sufficient solutions. The aim of this research is to propose a framework that uses text mining and multilevel association rules to efficiently structure Chinese incident reports and identify important incident patterns, providing an analysis of trends, rectification strategies, and guidance for safety management. A case study of a construction company in China was conducted using two years of incident data dated 2018-2019, including accidents and near misses. To identify incident elements, a pattern extraction workflow involving TextRank, and domain pertinence was devised based on the linguistic and writing styles of Chinese reports. A concept hierarchy was applied to determine the taxonomic relationships within the risk factors. Multilevel association rule mining was adopted and proven to deliver more comprehensive pattern indications. Comparative and cross-analysis of patterns in different time periods revealed the severity and temporal features of incidents as well as the effectiveness of preventive and precautionary measures. The results also highlight the importance of learning from near miss events. Decision makers can formulate countermeasures and management policies based on these results to improve safety performance.

Taking to "heart" the proposed legislation for permanent daylight saving time

In March 2022, the US Senate passed the Sunshine Protection Act that would abolish the biannual change in clocks each fall and spring and permanently adopt daylight saving time that aligns with the "spring forward" time change each March. A number of scientific and medical societies have endorsed the abolishment of the biannual clock change, but oppose the permanent adoption of daylight saving time. Instead, leading organizations such as the American Academy of Sleep Medicine (AASM) and the Society for Research on Biological Rhythms (SRBR) position statements highlight peer-reviewed evidence in favor of a permanent shift to standard time. The present perspectives will summarize some of the key AASM and SRBR recommendations, with a particular focus on the potential cardiovascular implications of a legislative change that would result in a permanent switch to either standard time or daylight saving time. Collectively, although there is building scientific consensus that abolishing the biannual time change has several sleep and circadian health benefits, the preponderance of evidence is opposite to the current legislation and instead suggests a permanent switch to standard time may offer the maximum health and safety benefits. This scientific evidence should be considered as the United States House of Representatives considers the Sunshine Protection Act.

Driving simulator performance worsens after the Spring transition to Daylight Saving Time

Circadian desynchrony and sleep deprivation related to the Spring transition to Daylight Saving Time (DST) have been associated with several unfavorable outcomes, including an increase in road traffic accidents. As previous work has mainly focused on analyzing historical crash/hospitalization data, there is virtually no literature investigating the effects of DST on specific driving performance indicators. Here, the effect of the Spring transition to DST on driving performance was investigated by means of a driving simulator experiment, in which participants completed two trials (one week distance, same time and day of the week) on exactly the same simulated route, the second trial taking place in the week after the transition to DST. Results were compared to those of a control group (who also underwent two trials, both before the DST transition), and documented significant worsening of driving performance after DST, as measured by a comprehensive set of simulator-derived indices.

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A simulator was used to study the effects of DST transition on driving behavior

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Several driving variables were negatively affected by DST transition

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These included reaction times, situation awareness and risk behavior

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DST-related circadian desynchrony is likely to result in driving impairment

Road traffic casualties in Great Britain at daylight savings time transitions: a causal regression discontinuity design analysis

OBJECTIVE

To determine whether daylight savings time (DST) transitions have an effect on road traffic casualties in Great Britain using causal regression discontinuity design (RDD) analysis. We undertake aggregate and disaggregate spatial and temporal analyses to test the commonly referenced sleep and light hypotheses.

DESIGN

The study takes the form of a natural experiment in which the DST transitions are interventions to be evaluated. Two outcomes are tested: (1) the total number of casualties of all severities and (2) the number of fatalities.

DATA

Data were obtained from the UK Department for Transport STATS19 database. Over a period of 14 years between 2005 and 2018, 311 766 total casualties and 5429 fatalities occurred 3 weeks on either side of the Spring DST transition and 367 291 total casualties and 6650 fatalities occurred 3 weeks on either side of the Autumn DST transition.

PRIMARY OUTCOME MEASURE

An RDD method was applied. The presence of a causal effect was determined via the degree of statistical significance and the magnitude of the average treatment effect.

RESULTS

All significant average treatment effects are negative (54 significant models out of 287 estimated), indicating that there are fewer casualties following the transitions. Overall, bootstrapped summary statistics indicate a reduction of 0.75 in the number of fatalities (95% CI -1.61 to -0.04) and a reduction of 4.73 in the number of total casualties (95% CI -6.08 to -3.27) on average per year at both the Spring and Autumn DST transitions combined.

CONCLUSIONS

The results indicate minor reductions in the number of fatalities following the DST transitions, and thus, our analysis does not support the most recent UK parliamentary estimate that there would be 30 fewer fatalities in Great Britain if DST was to be abolished. Furthermore, the results do not provide conclusive support for either the sleep or light hypotheses.

Impact of DST (Daylight Saving Time) on Major Trauma: A European Cohort Study

(1) Background: Approximately 73 countries worldwide implemented a daylight saving time (DST) policy: setting their clocks forward in spring and back in fall. The main purpose of this practice is to save electricity. The aim of the present study was to find out how DST affects the incidence and impact of seriously injured patients. (2) Methods: In a retrospective, multi-center study, we used the data recorded in the TraumaRegister DGU^® (TR-DGU) between 2003 and 2017 from Germany, Switzerland, and Austria. We compared the included cases 1 week before and after DST. (3) Results: After DST from standard time to summertime, we found an increased incidence of accidents of motorcyclists up to 51.58%. The result is consistent with other studies. (4) Conclusion: However, our results should be interpreted as a tendency. Other influencing factors, such as time of day and weather conditions, were not considered.

Marathon run performance on daylight savings time transition days: results from a natural experiment

Advancing clock times by 1 h in the spring to daylight savings time and setting clock times back 1 h in the autumn to standard time disrupts circadian timing, sleep and skilled motor behavior such as driving an automobile. It is unknown if endurance performance is impacted by daylight savings transition (DST). The natural experiment described here examined whether exposure to a DST in the 10 h prior to the start of a marathon race was associated with a different mean completion time compared to participants who ran the same course but were unexposed to a recent DST. The primary outcome was the average running time of finishers of United States marathons that were completed on either spring-DST or autumn-DST days in the years 2000-2018. Comparisons were made to results from the same marathon held in a different year that was not run on a DST day. Data were obtained from the public data base marathonguide.com/results. Analysis of the primary outcome used paired samples t-tests weighted by sample size. Spring and autumn data were analyzed separately. Eighteen spring and 29 autumn marathons met the inclusion criteria. Compared to control marathons, the weighted spring-DST performance was worse by 12.3 min (4.1%; P < .001) and equal to a moderate standardized effect size of 0.57 while autumn-DST was trivially worse by 1.4 min (0.5%), which was equivalent to an effect size of 0.13. Ambient temperatures for the DST and control races did not differ for either the spring (10.6 vs. 8.9℃; P = .212) or autumn marathons (7.6 vs. 9.3℃; P = .131). Within the limitations of a natural experiment research design, it is concluded that the findings support worse running performance in marathon races held in the spring on the day of transition to daylight savings time when there is a forced circadian change and sleep loss.

Effect of Daylight Saving Time clock shifts on white-tailed deer-vehicle collision rates

To devise effective measures for reducing hazardous wildlife-vehicle collisions, it is necessary to know when during the year accidents occur most frequently, and what factors cause the seasonal patterns. Daylight Saving Time (DST) 1-h clock-shifts around the spring and fall equinoxes at temperate zone latitudes are associated with increased vehicle accidents, attributed to driver error caused by disrupted sleep patterns and changes in visibility during peak driving times. Collision with deer is a significant cause of motor vehicle accidents in North America; in New York State alone, 65,000 vehicle accidents annually are caused by collision with white-tailed deer (Odocoileus virginianus). We asked whether white-tailed deer-vehicle collisions (DVC) increased in frequency after DST clock shifts in New York State, by analyzing 35,167 New York State DVC reports from 2005 to 2007. For the spring, when the clock is shifted an hour forward relative to sunrise (i.e. later sunrise and sunset), there was either no change or possibly a small decrease in workweek evening DVC after the clock shift. For fall, when the clock is shifted an hour back relative to sunrise (i.e. earlier sunrise and sunset), the DVC rate was far higher than spring. The DVC rate was higher after the clock shift than before, caused in part by an ongoing seasonal trend for increasing DVC associated with deer behavior around the time of rut, peaking about two weeks after the clock shift. However, there was also a reduction in workweek morning DVC after clock-shift, but an even greater increase in DVC in the evening. DVC rates are highest around dusk and during the fall, and the fall DST clock-shift caused more workweek commuter traffic to coincide with the annual hourly period of peak risk of DVC. We conclude that in New York State, DST clock-shift results in an increase in the number of DVC, and therefore injuries and property damage associated with such accidents. The justification for DST clock-shifts is controversial; when evaluating the benefits and costs, one should include the consequences for risk of wildlife-vehicle collisions, especially in regions where ungulate-vehicle accidents are frequent, and clock-shifts coincide with the rut or other periods of peak accident risk.

A chronobiological evaluation of the risks of canceling daylight saving time

The long-term impact of seasonal regulation of clocks (Daylight Saving Time) is analyzed showing that it helped to mitigate the advance of the phase of human activity during the twentieth century and the exposure to the hours of the dawn in winter. The increased risks induced by circadian misalignment around transition dates are balanced by a better alignment of social clocks to the natural day in summer and in winter.

Daylight Saving Time: Pros and Cons

The original rationale for the adoption of daylight saving time (DST) was to conserve energy; however, the effects of DST on energy consumption are questionable or negligible. Conversely, there is substantial evidence that DST transitions have the cumulative effect on sleep deprivation with its adverse health effects. In light of current evidence, the European Commission in 2018 decided that biannual clock change in Europe would be abolished. Current indirect evidence supports the adoption of perennial standard time, which aligns best with the human circadian system and has the potential to produce benefits for public health and safety.

Daylight saving time: an American Academy of Sleep Medicine position statement

None

The last several years have seen intense debate about the issue of transitioning between standard and daylight saving time. In the United States, the annual advance to daylight saving time in spring, and fall back to standard time in autumn, is required by law (although some exceptions are allowed under the statute). An abundance of accumulated evidence indicates that the acute transition from standard time to daylight saving time incurs significant public health and safety risks, including increased risk of adverse cardiovascular events, mood disorders, and motor vehicle crashes. Although chronic effects of remaining in daylight saving time year-round have not been well studied, daylight saving time is less aligned with human circadian biology-which, due to the impacts of the delayed natural light/dark cycle on human activity, could result in circadian misalignment, which has been associated in some studies with increased cardiovascular disease risk, metabolic syndrome and other health risks. It is, therefore, the position of the American Academy of Sleep Medicine that these seasonal time changes should be abolished in favor of a fixed, national, year-round standard time.

Measurable health effects associated with the daylight saving time shift

The transition to daylight saving time (DST) is beneficial for energy conservation but at the same time it has been reported to increase the risk of cerebrovascular and cardiovascular problems. Here, we evaluate the effect of the DST shift on a whole spectrum of diseases—an analysis we hope will be helpful in weighing the risks and benefits of DST shifts. Our study relied on a population-based, cross-sectional analysis of the IBM Watson Health MarketScan insurance claim dataset, which incorporates over 150 million unique patients in the US, and the Swedish national inpatient register, which incorporates more than nine million unique Swedes. For hundreds of sex- and age-specific diseases, we assessed effects of the DST shifts forward and backward by one hour in spring and autumn by comparing the observed and expected diagnosis rates after DST shift exposure. We found four prominent, elevated risk clusters, including cardiovascular diseases (such as heart attacks), injuries, mental and behavioral disorders, and immune-related diseases such as noninfective enteritis and colitis to be significantly associated with DST shifts in the United States and Sweden. While the majority of disease risk elevations are modest (a few percent), a considerable number of diseases exhibit an approximately ten percent relative risk increase. We estimate that each spring DST shift is associated with negative health effects–with 150,000 incidences in the US, and 880,000 globally. We also identify for the first time a collection of diseases with relative risks that appear to decrease immediately after the spring DST shift, enriched with infections and immune system-related maladies. These diseases’ decreasing relative risks might be driven by the documented boosting effect of a short-term stress (such as that experienced around the spring DST shift) on the immune system.

Over a quarter of the world population is subjected to the daylight saving time (DST) shift twice a year, which disrupts both human work and rest schedules and possibly the body’s biological clock. Several clinical studies have reported an increased risk of cerebrovascular and cardiovascular problems with DST shifts but little is known about other potential health effects. The DST shift represents a natural exposure experiment which allows us the unique opportunity of linking health outcomes to an external, state-wide event in the US and Sweden. We performed a comprehensive, phenome-wide screening of the putative health effects of the DST shift by analyzing two independent, country-scale health datasets, and found both adverse and protective associations with DST shifts in several clusters of conditions. We successfully verified previously reported associations, such as heart diseases and injuries, and identified new signals–for example, immune-related conditions. We suggest that the ramifications of daylight-saving time shifts should be acknowledged and further tested.

Daylight Saving Time Transitions: Impact on Total Mortality

In Europe and many countries worldwide, a half-yearly changing time scheme has been adopted with the aim of optimizing the use of natural daylight during working hours and saving energy. Because the expected net economic benefit was not achieved, the discussion about the optimal solution has been reopened with a shifted focus on social and health related consequences. We set out to produce evidence for this discussion and analysed the impact of daylight saving time on total mortality of a general population in a time series study on daily total mortality for the years 1970–2018 in the city of Vienna, Austria. Daily deaths were modelled by Poisson regression controlling for seasonal and long-term trend, same-day and 14-day average temperature, humidity, and day of week. During the week after the spring transition a significant increase in daily total mortality of about 3% per day was observed. This was not the case during the week after the fall transition. The increase in daily mortality as observed in the week after spring DST-transition is most likely causally linked to the change in time scheme.

The long term impact of Daylight Saving Time regulations in daily life at several circles of latitude

We analyze large scale (N ~ 10000) time use surveys in United States, Spain, Italy, France and Great Britain to ascertain seasonal variations in the sleep/wake cycle and the labor cycle after daylight saving time regulations have stood up for at least forty years. That is, not the usual search for the impact of the biannual transitions, but a search for how industrialized societies have answered to DST regulations at different circles of latitude. Results show that the labor cycle is equally distributed through seasons if measured in local time. It is an everyday experience which is a major outcome of DST. The sleep/wake cycle displays disturbances punctuated by solar events: sunrise, sunset and noon. In week-ends, under free preferences, sleep onset delays in summer, opposing to the regulation and following the delay in sunset time, while sleep offset advances, despite clock time already advanced in the spring transition. This advance still follows the advance in sunrise times. The best explanation for these findings is that human cycles are not misaligned by the size and direction of DST regulations, which explains the success of that practice. The sleep/wake cycle in Great Britain and France exhibit fewer statistically significant excursions than the sleep/wake cycle in Spain, Italy and United States, despite light and dark seasonal deviations are larger. That could be indicating that the preference for a seasonal regulation of time decreases with increasing latitude above 47°. The preferences for a seasonal regulation of clocks and for the choice of permanent summer time or permanent winter time are sketched from a previous report on human activity.

Tardiness Increases in Winter: Evidence for Annual Rhythms in Humans

Annual rhythms in humans have been described for a limited number of behavioral and physiological parameters. The aim of this study was to investigate time-of-year variations in late arrivals, sick leaves, dismissals from class (attendance), and grades (performance). Data were collected in Dutch high school students across 4 academic years (indicators of attendance in about 1700 students; grades in about 200 students). Absenteeism showed a seasonal variation, with a peak in winter, which was more strongly associated with photoperiod (number of hours of daylight) compared with other factors assessed (e.g., weather conditions). Grades also varied with time of year, albeit differently across the 4 years. The observed time-of-year variation in the number of sick leaves was in accordance with the literature on the seasonality of infectious diseases (e.g., influenza usually breaks out in winter). The winter peak in late arrivals was unexpected and requires more research. Our findings could be relevant for a seasonal adaptation of school schedules and working environments (e.g., later school and work hours in winter, especially at higher latitudes where seasonal differences in photoperiod are more pronounced).

Changes in Accident & Emergency Visits and Return Visits in Relation to the Enforcement of Daylight Saving Time and Photoperiod

Daylight saving time (DST) is a source of circadian disruption impinging on millions of people every year. Our aim was to assess modifications, if any, in the number, type, and outcome of Accident & Emergency (A&E) visits/return visits over the DST months. The study included 366,527 visits and 84,380 return visits to the A&E of Padova hospital (Northern Italy) over 3 periods between the years 2007 and 2016: period 1 (2 weeks prior to DST to 19 weeks after), period 2 (2 weeks prior to the return to "winter time" to 4 weeks after), and period 3 (5 consecutive non-DST weeks). For each A&E visit/return visit, information was obtained on triage severity code, main medical complaint, and outcome. Data were aggregated by day, cumulated over the years, and analyzed by generalized Poisson models. Generalized additive models for Poisson data were then used to include photoperiod as an additional covariate. An increase in A&E visits and return visits (mostly white codes, resulting in discharges) was observed a few weeks after the enforcement of DST and was significant over most weeks of period 1 (increase of ≈30 [2.8%] visits and ≈25 [10%] return visits per week per year). After the return to winter time, a decrease in absolute number of return visits was observed (mostly white codes, resulting in discharges), which was significant at weeks 3 and 4 of period 2 (decrease of ≅25 [10%] return visits per week per year). When photoperiod was taken into account, changes in A&E visits (and related white codes/discharges) were no longer significant, while changes in return visits (and related white codes/discharges) were still significant. In conclusion, changes in A&E visits/return visits were observed in relation to both DST and photoperiod, which are worthy of further study and could lead to modifications in A&E organization/staffing.