Daylight Saving Time Research Articles

The British Sleep Society position statement on Daylight Saving Time in the UK.

There is an ongoing debate in the United Kingdom and in other countries about whether twice-yearly changes into and out of Daylight Saving Time should be abolished. Opinions are divided about whether any abolition of Daylight Saving Time should result in permanent Standard Time, or year-long Daylight Saving Time. The British Sleep Society concludes from the available scientific evidence that circadian and sleep health are affected negatively by enforced changes of clock time (especially in a forward direction) and positively by the availability of natural daylight during the morning. Thus, our recommendation is that the United Kingdom should abolish the twice-yearly clock change and reinstate Standard Time throughout the year.

Productivity losses in the transition to Daylight Saving Time: Evidence from hourly GitHub activity

Using data on GitHub users around the world, we estimate the effects of transitions to Daylight Saving Time on worker activity. In daily activity, transitions appear short lived—there is evidence of two days of declines before activity returns to baseline levels. However, hourly analysis reveals a transition to Daylight Saving Time that is much longer—losses appear in the early working hours of work days into a second week following the initiation of Daylight Saving Time.

TCT-815 The Impact of Daylight Savings Time on Clinical Outcomes in Patients With Acute Myocardial Infarction: Insights From the NCDR CathPCI Registry

TCT-815 The Impact of Daylight Savings Time on Clinical Outcomes in Patients With Acute Myocardial Infarction: Insights From the NCDR CathPCI Registry

A Call From Health Care Providers and a Patient to End Daylight Savings Time

A Call From Health Care Providers and a Patient to End Daylight Savings Time

The natural experiment of daylight saving time (DST) and acute myocardial infarction (AMI): A meta-analysis of studies in ten countries

The natural experiment of daylight saving time (DST) and acute myocardial infarction (AMI): A meta-analysis of studies in ten countries

Does sunlight exposure predict next-night sleep? A daily diary study among U.S. adults.

Poor sleep is becoming increasingly prevalent and is associated with adverse health outcomes. Sunlight exposure may improve sleep by regulating circadian rhythms, increasing vitamin D, and influencing melatonin production. However, research on the sunlight-sleep association is limited, especially outside of cross-sectional designs. This study examined associations between daily self-reported sunlight exposure and next-night sleep quality in 103 adults for up to 70 days. The timing of sunlight exposure predicted next-night sleep quality. Specifically, morning sunlight exposure, relative to no sunlight, predicted better sleep quality based on responses to the brief Pittsburg Sleep Quality Index. Duration of sunlight exposure was generally not associated with sleep quality. Morning sunlight may regulate circadian rhythms, subsequently improving sleep. Findings have potential implications for sleep interventions and daylight savings time policies. Future research should test whether morning sunlight exposure can enhance the effectiveness of sleep interventions.

Daylight Saving Time Transitions and Risk of Heart Attack—a Systematic Review and Meta-Analysis.

The health risks of daylight saving time transitions are intensely debated. Disturbed circadian rhythms and lack of sleep after transitions might increase the risk of acute myocardial infarction (AMI). The only meta-analysis on the risk of AMI has now been considerably expanded. In this systematic review and meta-analysis (including meta-regressions and sensitivity analyses), we examine the frequency of AMI in the first few weeks after daylight saving time transitions (OSF registration www.doi.org/10.17605/OSF.IO/7CFKS). Eight databases were searched for pertinent literature up to September 2023. Authors were contacted for additional information. Study quality was rated using the Newcastle-Ottawa Scale. Twelve studies from ten countries were included in the meta-analysis. Nine were of adequate quality, and three were of good quality. The pooled relative risk (RR) of AMI after daylight saving time onset (spring) was 1.04 (95% confidence interval [1.02; 1.07], I2: 57.3%), and 1.02 ([0.99; 1.05], I2: 51.6%) after daylight saving time offset (autumn). Recalculation after the exclusion of one study with inconsistencies yielded pooled RR values of 1.04 [1.01; 1.06] and 1.00 [0.99; 1.02], with the spring results being heterogeneous (I2: 56.9%) and the autumn results homogeneous (I2: 17.1%). Current evidence suggests that there may be an increased risk of AMI after the spring transition, although there is moderate to marked heterogeneity among the studies that support this conclusion. More easily interpretable studies, such as those already conducted in the field of economics, should clarify associations with the aid of discontinuity regression and placebo tests. To this end, comparative risk analyses using years or places wherein daylight saving time was not practiced would be suitable.

Daylight Saving Time Transitions and Risk of Heart Attack.

The health risks of daylight saving time transitions are intensely debated. Disturbed circadian rhythms and lack of sleep after transitions might increase the risk of acute myocardial infarction (AMI). The only meta-analysis on the risk of AMI has now been considerably expanded. In this systematic review and meta-analysis (including meta-regressions and sensitivity analyses), we examine the frequency of AMI in the first few weeks after daylight saving time transitions (OSF registration www.doi.org/10.17605/OSF.IO/7CFKS). Eight databases were searched for pertinent literature up to September 2023. Authors were contacted for additional information. Study quality was rated using the Newcastle-Ottawa Scale. Twelve studies from ten countries were included in the meta-analysis. Nine were of adequate quality, and three were of good quality. The pooled relative risk (RR) of AMI after daylight saving time onset (spring) was 1.04 (95% confidence interval [1.02; 1.07], I2: 57.3%), and 1.02 ([0.99; 1.05], I2: 51.6%) after daylight saving time offset (autumn). Recalculation after the exclusion of one study with inconsistencies yielded pooled RR values of 1.04 [1.01; 1.06] and 1.00 [0.99; 1.02], with the spring results being heterogeneous (I2: 56.9%) and the autumn results homogeneous (I2: 17.1%). Current evidence suggests that there may be an increased risk of AMI after the spring transition, although there is moderate to marked heterogeneity among the studies that support this conclusion. More easily interpretable studies, such as those already conducted in the field of economics, should clarify associations with the aid of discontinuity regression and placebo tests. To this end, comparative risk analyses using years or places wherein daylight saving time was not practiced would be suitable.

Long-term effects of daylight saving time on driving fatigue

The study of the relationship between Daylight Saving Time (DST) and road safety has yielded contrasting results, most likely in relation to the inability of crash-database approaches to unravel positive (ambient lighting-related) and negative (circadian/sleep-related) effects, and to significant geographical differences in lighting-related effects. The aim of this study was to investigate the effects of DST on driving fatigue, as measured by driving-based, physiological and subjective indicators obtained from a driving simulator experiment. Thirty-seven participants (73 % males, 23 ± 2 years) completed a series of 50-min trials in a monotonous highway environment: Trial 1 was in the week prior to the Spring DST transition, Trial 2 in the following week, and Trial 3 in the fourth week after the transition. Thirteen participants returned for Trial 4, in the week prior to the Autumn switch to civil time, and Trial 5 in the following week. Significant adverse effects of DST on vehicle lateral control and eyelid closure were documented in Trial 2 and Trial 3 compared to Trial 1, with no statistical differences between Trials 2 and 3. Further worsening in vehicle lateral control was documented in Trials 4 and 5. Eyelid closure worsened up to Trial 4, and improved in Trial 5. Participants were unaware of their worsening performance based on subjective indicators. In conclusion, DST has a detrimental impact on driving fatigue during the whole time during which it is in place. Such an impact is comparable, for example, to that associated with driving with a blood alcohol concentration of 0.5 g/L.

Improving adjustment to daylight saving time transitions with light

Daylight saving time (DST) is currently utilized in many countries with the rationale that it enhances the alignment between daylight hours and activity peaks in the population. The act of transitioning into and out of DST introduces disruptions to the circadian rhythm, thereby impacting sleep and overall health. Despite the substantial number of individuals affected, the consequences of this circadian disruption have often been overlooked. Here, we employ a mathematical model of the human circadian pacemaker to elucidate how the biological clock interacts with daytime and evening exposures to both natural and electrical light. This interaction plays a crucial role in determining the adaptation to the 1 hour time zone shift imposed by the transition to or from DST. In global discussions about DST, there is a prevailing assumption that individuals easily adjust to DST transitions despite a few studies indicating that the human circadian system requires several days to fully adjust to a DST transition. Our study highlights that evening light exposure changes can be the main driving force for re-entrainment, with chronobiological models predicting that people with longer intrinsic period (i.e. later chronotype) entrain more slowly to transitions to or from DST as compared to people with a shorter intrinsic period (earlier chronotype). Moreover, the model forecasts large inter-individual differences in the adaptation speed, in particular during the spring transition. The predictions derived from our model offer circadian biology-based recommendations for light exposure strategies that facilitate a more rapid adaptation to DST-related transitions or travel across a single time zone. As such, our study contributes valuable insights to the ongoing discourse on DST and its implications for human circadian rhythms.

Losing sleep at the international market: Daylight Saving Time and exchange rates

This article examines the impact of the move into and out of Daylight Saving Time (DST) on bilateral exchange rates. When a country starts DST, the value of its currency depreciates, which is reversed when the country exits DST.

Defining daytime in the day-dark approach to measuring the pedestrian reassurance of road lighting

In the day-dark approach to measuring the contribution of road lighting to pedestrian reassurance, reassurance is evaluated in daylight and after dark. In previous studies, the daylight and after dark evaluations were carried out at different times of day. Other factors, such as the presence of other people, are likely to vary with time of day, and hence this confounds conclusions about the effectiveness of road lighting. In this study, we conducted a day-dark field study of pedestrian reassurance but with the daylight evaluation carried out at two times of the day, one at around mid-day and one at the same time of day as the after dark evaluation, achieved by taking advantage of the biannual daylight savings clock change. These data did not suggest any significant effects of time of day on the daylight evaluations of pedestrian reassurance.

Medical malpractice litigation and daylight saving time.

Daylight saving time (DST) constitutes a natural quasi-experiment to examine the influence of mild sleep loss and circadian misalignment. We investigated the acute effects of spring transition into DST and the chronic effects of DST (compared to standard time) on medical malpractice claims in the United States over 3 decades. We analyzed 288,432 malpractice claims from the National Practitioner Data Bank. To investigate the acute effects of spring DST transition, we compared medical malpractice incidents/decisions 1 week before spring DST transition, 1 week following spring DST transition, and the rest of the year. To investigate the chronic effects of DST months, we compared medical malpractice incidents/decisions averaged across the 7-8 months of DST vs the 4-5 months of standard time. With regard to acute effects, spring DST transitions were significantly associated with higher payment decisions but not associated with the severity of medical incidents. With regard to chronic effects, the 7-8 DST months were associated with higher average payments and worse severity of incidents than the 4-5 standard time months. The mild sleep loss and circadian misalignment associated with DST may influence the incidence of medical errors and decisions on medical malpractice payments both acutely and chronically. Gao C, Lage C, Scullin MK. Medical malpractice litigation and daylight saving time. J Clin Sleep Med. 2024;20(6):933-940.

EXPRESS: Spring Forward = Fall Back? the Effect of Daylight Saving Time Change on Consumers’ Unhealthy Behavior

Prior research documents deleterious consequences of the annual clock change to daylight saving time in many contexts, but little is known about the effect the policy has on consumer behavior. While policy debates around ending seasonal clock changes continue, millions of consumers worldwide are potentially adversely affected by the time change. Drawing on the notions of sleepiness and self-control, the authors propose a framework of how the onset of daylight saving time increases unhealthy behavior. The hypotheses are tested via two studies cast in the difference-in-differences modeling framework capturing consumption before and after the time change and across consumers who experience the transition versus who do not. Results of the first study suggest that the onset of daylight saving time increases calorie consumption from packaged snacks that are largely unhealthy, specifically in the evening and on cloudy days. The effect of the end of daylight saving time is not significant, suggesting an overall asymmetric effect of the time change on unhealthy behavior. Study 2 reveals that the onset of daylight saving time decreases fitness center visits, particularly for consumers without healthy consumption habits and with high transaction costs. Analysis of social media data suggests that consumers find the time change disruptive. Overall, the findings imply that public policy makers and businesses should find ways to support consumers around the onset of daylight saving time.

Evaluation of the effect of daylight saving time on household lighting saving potential in six highly urbanised Chinese cities

ABSTRACT (Double) Daylight Saving Time (DST/DDST) synchronizes human daily activities with sunlight hours, aiming to save energy. China implemented DST/DDST in 1986 and annulled it in 1991, which has not since been observed. This study aims to revisit the household lighting energy-saving potentials of DST/DDST implementation in six representative highly urbanized Chinese cities across different latitudes and within different climate zones, based on the electricity consumption behaviour of Chinese people in the 2020s. We constructed country-specific Multiple Linear Regression (MLR) analysis models interrelated with the local characteristic features of the DST/DDST in China, including latitude, age structure, industrial structure, get-up and bedtime schedules. The results showed the following: (1) Both DST and DDST can effectively reduce household lighting consumption in all the studied case cities, while DDST has a superior energy-saving potential; (2) Considering China-specific lifetime schedules, April to October is the most recommended duration for DST/DDST implementation; (3) Northern cities in China exhibit greater potential for energy savings in lighting than southern regions. (4) Cities with larger portions of primary industry have more household lighting-saving potential in China. Based on the obtained results, monthly data and separate statistical data on household lighting could help promote the precision of regression models.

Daylight Saving Time and Self-Reported Bruxism Manifestations: First Results From a Multicentric, Case-Control Study

Daylight Saving Time and Self-Reported Bruxism Manifestations: First Results From a Multicentric, Case-Control Study

Daylight saving time was not associated with a change in suicide rates in Austria, Switzerland and Sweden.

Some studies have reported an increase in suicides after the start of daylight saving time (DST), but the evidence is mixed and more research about proposed mechanisms (disrupted sleep, changing light exposure) is needed. In our preregistered study, we analyzed change in suicide rates in the 2 weeks before/after DST, based on data between 1980 and 2022 from Austria, Switzerland and Sweden, using Poisson regression models and changepoint analyses. To explore the impact of disrupted sleep, we repeated the analysis for retired people who are likely less bound to DST, and for younger people. To explore the effect of changed daylight exposure, we repeated the analysis for northern and southern regions because twilight and daylight exposure varies by latitude. Suicide rates did not significantly increase after the start of DST (adjusted incidence rate ratio IRR = 0.98, 95% CI 0.91-1.06, P = 0.66, n = 13 362 suicides) or after DST ended (adjusted IRR = 0.99, 95% CI 0.91-1.07, P = 0.76, n = 12 319 suicides). There were no statistically significant findings among younger or older subgroups and also not in Sweden and Austria/Switzerland. No changepoints were detected. There were no significant changes in suicide rates associated with DST and no clear evidence to support proposed mechanisms (light exposure, disruption of sleep). Our study is one of the largest and was adequately powered. Nonetheless, even larger studies to detect smaller effects could be important to inform the debate about harms and benefits of DST.

Author Response: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.

Author Response: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.

Reader Response: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.

Reader Response: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.

Editors' Note: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.

Editors' Note: Effects of Season and Daylight Saving Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging.