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.

Summertime and the drivin' is easy? Daylight saving time and vehicle accidents

We investigate how exogenous variation in daylight caused by Daylight Saving Time affects road safety as measured by the count of vehicle crashes. We use administrative daily data from Greece covering the universe of all types of recorded vehicle accidents during the 2006-2016 period. Our regression discontinuity estimates support an ambient light mechanism that reduces the counts of serious vehicle accidents during the Spring transition and increases the count of minor ones during the Fall transition. The effects are driven from the hour intervals that are mostly affected from seasonal clock changes. We then discuss the potential cost implications of those seasonal transitions. In light of the talks about abolishing seasonal clock changes in the European Union (EU), our findings are policy relevant and can inform the public debate as empirical evidence for the block is scarce.

Daylight Saving Time transitions and Cardiovascular Disease in Andalusia: Time Series Modeling and Analysis Using Visibility Graphs

The present study aimed to determine whether transitions both to and from daylight saving time (DST) led to an increase in the incidence of hospital admissions for major acute cardiovascular events (MACE). To support the analysis, natural visibility graphs (NVGs) were used with data from Andalusian public hospitals between 2009 and 2019. We calculated the incidence rates of hospital admissions for MACE, and specifically acute myocardial infarction and ischemic stroke during the 2 weeks leading up to, and 2 weeks after, the DST transition. NVG were applied to identify dynamic patterns. The study included 157 221 patients diagnosed with MACE, 71 992 with AMI (42 975 ST-elevation myocardial infarction (STEMI) and 26 752 non-ST-elevation myocardial infarction (NSTEMI)), and 51 420 with ischemic stroke. Observed/expected ratios shown an increased risk of AMI (1.06; 95% CI (1.00-1.11); P = .044), NSTEMI (1.12; 95% CI (1.02-1.22); P = .013), and acute coronary syndrome (1.05; 95% CI (1.00-1.10); P = .04) around the autumn DST. The NVG showed slight variations in the daily pattern of pre-DST and post-DST hospitalization admissions for all pathologies, but indicated that the increase in the incidence of hospital admissions after the DST is not sufficient to change the normal pattern significantly.

Effects of Season and Daylight Savings Time Shifts on Sleep Symptoms: Canadian Longitudinal Study on Aging

BACKGROUND AND OBJECTIVES

There has been conflicting evidence regarding the association between seasonal changes and daylight-savings time and sleep disorders. This topic is of current particular interest, as the United States and Canada are considering the elimination of seasonal clock changes. The aim of this study is to compare sleep symptoms among participants who were interviewed in different seasons, and before/after the transition into daylight saving time (DST) and standard time (ST).

METHODS

30,097 people aged 45-85 years taking part in the Canadian Longitudinal Study on Aging (CLSA) were studied. Participants completed a questionnaire on sleep duration, satisfaction, sleep-onset insomnia, sleep-maintenance insomnia, and hypersomnolence symptoms. Sleep disorders were compared between participants who were interviewed during different seasons and at different times of the year (DST/ST). Data was analyzed using Chi Square, ANOVA, binary logistic, and linear regression tests.

RESULTS

Among participants interviewed in different seasons, we found no difference in dissatisfaction with sleep, sleep-onset, sleep-maintenance, and hypersomnolence. Those interviewed in summer had slightly shorter sleep duration compared to winter (6.76±1.2 vs. 6.84±1.3 hours). Participants interviewed one week before versus one week after DST transition showed no difference in sleep symptoms, except for a 9-minute decrease in sleep duration a week after transition. However, those who were interviewed a week after transition to ST compared to a week before reported more dissatisfaction with sleep (28% vs. 22.6%, adjusted odds ratio [95%CI]=1.34 [1.02,1.76]), higher sleep-onset insomnia (7.1% vs. 3.3%, AOR=2.26 [1.19,4.27]), higher sleep-maintenance insomnia (12.9% vs. 8.2%, AOR=1.64 [1.02,2.66]), and more hypersomnolence with adequate sleep (7.3% vs. 3.6%, AOR=2.08 [1.14,3.79].

DISCUSSION

We found small seasonal variations in sleep duration but no difference in other sleep symptoms. The transition from DST to ST was associated with a transient increase in sleep disorders.

It is time to abolish the clock change and adopt permanent standard time in the United States: a Sleep Research Society position statement

Daylight saving time (DST) refers to the practice of advancing clock time by 1 h each spring, with a return (setting back) to standard time (ST) each fall. Numerous sleep and circadian societies other than the Sleep Research Society have published statements in support of permanent ST, and permanent ST has also received support from multiple medical societies and organizations. This perspective discusses the positive and negative health and economic consequences of permanent DST, permanent ST, and maintaining the status quo (DST for part of the year). After a thorough review of the existing literature, the SRS advocates the adoption of permanent ST.

Permanent daylight saving time would reduce deer-vehicle collisions

Overlap between wildlife and human activity is key to causing wildlife-vehicle collisions, a globally pervasive and growing source of wildlife mortality.^1,2 Policies regarding clock time often involve abrupt seasonal shifts in human activity, potentially influencing rates of human-wildlife conflict. Here, we harness the biannual shift between standard and daylight saving time as a natural experiment to reveal how the timing of human activity influences deer-vehicle collisions. Based on 1,012,465 deer-vehicle collisions and 96 million hourly traffic observations across the United States, we show that collisions are 14 times more frequent 2 hours after sunset than before sunset, highlighting the importance of traffic during dark hours as a key determinant of deer-vehicle collision risk. The switch from daylight saving to standard time in autumn causes peak traffic volumes to shift from before sunset to after sunset, leading to a 16% spike in deer-vehicle collisions. By reducing traffic after dark, our model predicts that year-round daylight saving time would prevent 36,550 deer (Odocoileus sp.) deaths, 33 human deaths, 2,054 human injuries, and US$1.19 billion in collision costs annually. In contrast, permanent standard time is predicted to increase collisions by an even larger magnitude, incurring an additional US$2.39 billion in costs. By targeting the temporal dimension of wildlife-vehicle collisions, strategies such as year-round daylight saving time that reduce traffic during dark hours, especially during the breeding season of abundant ungulates, would yield substantial benefits for wildlife conservation and reduce the social and economic costs of deer-vehicle collisions.

Saving light, losing lives: How daylight saving time impacts deaths from suicide and substance abuse

This paper estimates the impact of Daylight Saving Time (DST) on deaths from suicide and substance abuse in the United States. Using Multiple Cause-of-Death Mortality Data from the National Vital Statistics System of the National Center for Health Statistics from 1979 to 1988, the effect is identified in two ways: a regression discontinuity design that exploits discrete time changes in the Spring and Fall; and a fixed effects model that uses a policy change and a switching mechanism that introduces random variation to DST's start and end dates. This is one of the first attempts to estimate the impact of DST on deaths due to suicide and substance abuse and the first to use either identification strategy. The results from both methods suggest that the sleep disruptions during the Spring transition cause the suicide rate to rise by 6.25 percent and the death rate from suicide and substance abuse combined to increase by 6.59 percent directly after the time change. There is no evidence for any change in these outcomes during the Fall transition. The contrasting results from Spring to Fall suggest the entire effect can be attributed to disruptions in sleep patterns rather than changes in ambient light exposure.

Sleep and Alcohol Use Patterns During Federal Holidays and Daylight Saving Time Transitions in the United States

We conducted a retrospective observational study using remote wearable and mobile application data to evaluate whether US public holidays or Daylight Saving Time transitions were associated with significant changes in sleep behaviors, including sleep duration, sleep onset and offset, and the consistency of sleep timing, as well as changes in the point prevalence of alcohol use. These metrics were analyzed using objective, high resolution sleep-wake data (10,350,760 sleep episodes) and 5,777,008 survey responses of 24,250 US subscribers (74.5% male; mean age of 37.6 ± 9.8 years) to the wrist-worn biometric device platform, WHOOP (Boston, Massachusetts, United States), who were active users during 1 May 2020, through 1 May 2021. Compared to baseline, statistically significant differences in sleep and alcohol measures were found on most DST transitions, US public holidays, and their eves. For example, New Year's Eve corresponded with a sleep consistency decrease of 13.8 ± 0.3%, a sleep onset delay of 88.9 ± 3.2 min (00:01 vs. 22:33 baseline) later, a sleep offset delay of 78.1 ± 3.1 min (07:56 vs. 06:39), and an increase in the prevalence of alcohol consumption, with more than twice as many participants having reported alcohol consumption [+138.0% ± 6.7 (74.2% vs. 31.2%)] compared to baseline. In this analysis of a non-random sample of mostly male subscribers conducted during the COVID-19 pandemic, the majority of US public holidays and holiday eves were associated with sample-level increases in sleep duration, decreases in sleep consistency, later sleep onset and offset, and increases in the prevalence of alcohol consumption. Future work would be warranted to explore the generalizability of these findings and their public health implications, including in more representative samples and over longer time intervals.

A Data-Informed Perspective on Public Preferences for Retaining or Abolishing Biannual Clock Changes

Scientific, public, and political discourse around the perennial changing of the clocks during the transitions into and out of daylight saving time (DST) is a touchstone issue for the translation of fundamental chronobiology into societal impacts. The Society for Research on Biological Rhythms, along with other sleep science bodies, has issued a position statement that advocates for the abolition of the biannual clock changes and the adoption of permanent standard time for the optimization of population circadian health. However, there is a paucity of data on preexisting public perceptions and preferences with regard to these issues. In this perspective, we examine 5 issues that we believe are pertinent for chronobiologists to consider to enable effective advocacy on these policies; in particular, we discuss public preference for permanent DST and steps that may need to be taken to understand this preference. We inform our discussion with reference to cross-sectional studies we undertook in Spring 2020 and Fall 2019, around the transition out of and into DST Ireland. We conclude that there appears to be a gap between existing public perceptions and preferences around the clock changes and chronobiological and sleep science-informed positions, and that the chronobiology community may benefit from interdisciplinary collaboration with colleagues with specific social sciences expertise to most effectively advocate for these research-informed positions.

Longitudinal Location Influences Preference for Daylight Saving Time

The chronobiology community advocates ending the biannual practice in many countries of adjusting their clocks to observe Daylight Saving Time (DST). Many governments are actively considering abandoning this practice. While sleep and circadian experts advocate the adoption of year-round standard time, most jurisdictions are instead considering permanent DST. In guiding advocacy, it is useful to understand the factors that lead governments and citizens to prefer the various options. In October 2021, the Canadian province of Alberta conducted a province-wide referendum on adopting year-round DST, in which more than 1 million valid votes were cast. As this referendum was tied to province-wide municipal elections, the results of the referendum were reported at the community level, allowing a geospatial analysis of preference for permanent DST. While the referendum proposal was narrowly defeated (49.8% in favor), a community-level analysis demonstrated a significant East-West gradient, with eastern communities more strongly in favor and western communities more strongly opposed to the year-round DST. Community size and latitudinal position also contributed to preference, with smaller and more northern communities showing more preference for year-round DST. These findings help identify how geospatial location can influence how citizens feel about the various time options and can further help guide public advocacy efforts by the sleep and circadian communities.

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.

Assessment of the number of admissions for road traffic collisions and severity of injury in daylight saving time and permanent daylight saving time periods

BACKGROUND/AIM

Permanent daylight saving time has been implemented in Turkey since 2016. The present study determines the characteristics of road traffic collisions in the short-term, trauma severity, and whether permanent daylight saving time has an impact on these parameters.

MATERIALS AND METHODS

Drivers admitted because of road traffic collisions to a tertiary care university hospital emergency service two weeks before and after the transition to wintertime in 2014 and 2015 and summertime in 2015 and 2016 as well as those admitted two weeks before and after the same period with permanent daylight saving time in 2016 and 2017 wintertime and 2017 and 2018 summertime were included in the study. Trauma severity was measured using the Injury Severity Score.

RESULTS

The study analysed the data of 710 patients. There was no statistically significant difference was found between admissions in the summertime and permanent daylight saving time periods in terms of gender, time of admission, week of admission, Injury Severity Score and outcome (P > .05 for all values).

CONCLUSIONS

In this study, we examined the short-term effects of daylight saving time on road traffic collisions, and demonstrated that it had no impact on the number or time of admission, trauma severity and patient outcomes. More comprehensive studies covering longer periods can be performed across the country.

Acute Myocardial Infarction and Daylight Saving Time Transitions: Is There a Risk?

Available evidence on the risk of acute myocardial infarction (AMI) in the days after the spring daylight saving time (DST) transition suggests either a modest increase or no risk increase. Partial sleep deprivation and enhanced circadian clock misalignment have been implicated as the underlying mechanisms for increased AMI risk, probably via enhanced thrombo-inflammatory processes and activation of the sympathetic nervous system. Most of the studies, as we suggest as a perspective here, have used potentially inappropriate control periods, including the two post-transitional weeks, because adjustment after the spring DST transition lasts at least four weeks for all chronotypes and probably even beyond this period for late chronotypes. The most plausible conclusions, at the moment, for the risk of AMI after the spring DST transition are: (1) the risk is increased, (2) a relatively modest risk increase could be currently underestimated or in some studies undetected, (3) late chronotypes and/or individuals with high levels of social jetlag (a proxy for circadian clock misalignment) could be more affected by the phenomenon, and (4) underlying pathophysiological mechanisms should be further explored. As a significant part of world’s population continues to be affected by the biannual clock change, the question of increased AMI risk in the post-transitional period remains an intriguing public health issue.

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.

Perspective: Daylight Saving Time-An Advocacy for a Balanced View and against Fanning Fear

As experts, scientists must inform the public and political actors about relevant topics by providing a well-balanced analysis and overview of existing as well as missing scientific evidence. Particularly in cases where evidence is not solid, they must remain objective and not fan fear. Maintaining good scientific practice can be challenging, especially when a debate is emotionally charged and simple answers for complex issues are demanded. Recently, this was the case with the debate about (perennial) standard time vs. daylight saving time. In this publication, we address the common misconceptions and pitfalls for good scientific practice that accompany this discussion and deduce suggestions for future directions, which may help resolve them. Beyond this, we argue that it is not wise to simply "explain away" the public opinion or preference and we therefore recommend strategies that could support a discourse aiming at getting the public "on board". Finally, we suggest that, in societies where the light environment is becoming increasingly complex, it may be time to reconsider the prevailing current relationships between solar and social clocks.

A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk

There is evidence that the spring Daylight Saving Time (DST) transition acutely increases motor vehicle accident (MVA) risk ("DST effect"), which has been partly attributed to sleep deprivation and circadian misalignment [1-6]. Because spring DST also shifts clock time 1 h later, mornings are darker and evenings brighter, changing illumination conditions for peak traffic density. This daytime-dependent illumination change ("time of day effect") is hypothesized to result in DST-associated afternoon and evening accident risk reductions [2, 5, 7]. Furthermore, sunrise and local photoperiod timing depend on position in time zone. The sun rises at an earlier clock time in the eastern regions of a given time zone than in the western regions, which is thought to induce higher levels of circadian misalignment in the west than in the east ("time zone effect") [8, 9]. This study evaluated the acute consequences of the DST transition on MVAs in a chronobiological context, quantifying DST, time of day, and time zone effects. We used large US registry data, including 732,835 fatal MVAs recorded across all states (1996-2017), and observed that spring DST significantly increased fatal MVA risk by 6%, which was more pronounced in the morning and in locations further west within a time zone. DST-associated MVA risk increased even in the afternoon hours, despite longer daylight hours. The MVA risk increase waned in the week subsequent to DST, and there were no effects of the fall-back transition to Standard Time (ST) on MVA risk, further supporting the hypothesis that DST-transition-associated, preventable circadian misalignment and sleep deprivation might underlie MVA risk increases.

Seasonal Clock Changes Are Underappreciated Health Risks-Also in IBD?

Today, daylight saving time is observed in nearly 80 countries around the world, including the European Union, the USA, Canada, and Russia. The benefits of daylight saving time in energy management have been questioned since it was first introduced during World War I and the latest research has led to varying results. Meanwhile, adverse effects of seasonal time shifts on human biology have been postulated and the European Union is planning to abandon the biannual clock change completely. Medical studies have revealed a correlation of seasonal time shifts with increased incidences of several diseases including stroke, myocardial infarction, and unipolar depressive episodes. Moreover, studies in mice have provided convincing evidence, that circadian rhythm disruption may be involved in the pathogenesis of inflammatory bowel diseases, mainly by disturbing the intestinal barrier integrity. Here, we present previously unpublished data from a large German cohort indicating a correlation of seasonal clock changes and medical leaves due to ulcerative colitis and Crohn's disease. Furthermore, we discuss the health risks of clock changes and the current attempts on reforming daylight saving time from a medical perspective.

Daylight saving time transitions are not associated with increased seizure incidence

OBJECTIVE

Given the known association of daylight saving time (DST) transitions with increased risk of accidents, heart attack, and stroke, we aimed to determine whether seizures, which are reportedly influenced by sleep and circadian disruption, also increased in frequency following the transition into DST.

METHODS

Using Seizure Tracker's self-reported data from 12 401 individuals from 2008-2016, 932 717 seizures were assessed for changes in incidence in relation to DST transitions. Two methods of standardization-z scores and unit-scaled rate ratios (RRs)-were used to compare seizure propensities following DST transitions to other time periods.

RESULTS

As a percentile relative to all other weeks in a given year, absolute seizure counts in the week of DST fell below the median (DST seizure percentiles mean ± SD: 19.68 ± 16.25, P = 0.01), which was concordant with weekday-specific comparisons. Comparatively, RRs for whole-week (1.06, 95% confidence interval [CI] 1.02-1.10, P = 0.0054) and weekday-to-weekday (RR range 1.04-1.16, all P < 0.001) comparisons suggested a slightly higher incidence of seizures in the DST week compared to all other weeks of the year. However, examining the similar risk of the week preceding and following the DST-transition week revealed no significant weekday-to-weekday differences in seizure incidence, although there was an unexpected, modestly decreased seizure propensity in the DST week relative to the whole week prior (RR 0.94, 95% CI 0.91-0.96, P < 0.001).

SIGNIFICANCE

Despite expectations that circadian and sleep disruption related to DST transitions would increase the incidence of seizures, we found little substantive evidence for such an association in this large, longitudinal cohort. Although large-scale observational/epidemiologic cohorts can be effective at answering such questions, additional covariates (eg, sleep duration, seizure type, and so on) that may underpin the association were not able available, so the association has not definitively been ruled out.

Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis

Background: The available evidence on the effects of daylight saving time (DST) transitions on major cardiovascular diseases is limited and conflicting. We carried out the first meta-analysis aimed at evaluating the risk of acute myocardial infarction (AMI) following DST transitions. Methods: We searched cohort or case-control studies evaluating the incidence of AMI, among adults (≥18 y), during the weeks following spring and/or autumn DST shifts, versus control periods. The search was made in MedLine and Scopus, up to 31 December 2018, with no language restriction. A summary odds ratio of AMI was computed after: (1) spring, (2) autumn or (3) both transitions considered together. Meta-analyses were also stratified by gender and age. Data were combined using a generic inverse-variance approach. Results: Seven studies (>115,000 subjects) were included in the analyses. A significantly higher risk of AMI (Odds Ratio: 1.03; 95% CI: 1.01–1.06) was observed during the two weeks following spring or autumn DST transitions. However, although AMI risk increased significantly after the spring shift (OR: 1.05; 1.02–1.07), the incidence of AMI during the week after winter DST transition was comparable with control periods (OR 1.01; 0.98–1.04). No substantial differences were observed when the analyses were stratified by age or gender. Conclusion: The risk of AMI increases modestly but significantly after DST transitions, supporting the proposal of DST shifts discontinuation. Additional studies that fully adjust for potential confounders are required to confirm the present findings.

Self-reported discomfort associated with Daylight Saving Time in Brazilian tropical and subtropical zones

BACKGROUND

Daylight Saving Time (DST) annually moves clocks 1 hour forward, when daytime is longer than night. Previous studies from medium and high latitude locations have pointed to a disruptive effect of DST on human circadian rhythms. Since Brazil is an equatorial country implementing DST, a different relationship between photic and social synchronisers may interfere with DST effects.

AIM

To explore the prevalence and duration of self-reported discomfort related to DST among Brazilian residents (latitude 12-33° S, longditude 39-57° W). It was hypothesised that an elevated prevalence of self-reported discomfort would be found in Brazil, due to the pronounced uncoupling between social and geophysical synchronisers.

SUBJECTS AND METHODS

In total, 12 467 volunteers completed a web-based, Brazilian version of Horne-Östberg Morningness-Eveningness Questionnaire, provided demographic information, and answered questions related to DST complaints (discomfort, duration of discomfort).

RESULTS

Of the total sample, 45.43% reported no discomfort related to DST, with meaningful proportions for all chronotypes. However, eveningness was most associated with discomfort. About one fourth of the total sample reported discomfort over the whole DST period. Gender interaction is largely supported by these results.

CONCLUSIONS

DST at low latitude locations may be disruptive for circadian rhythms, since seasonality of sunrise near the equator is negligible or very mild.

Impact of daylight saving time on road traffic collision risk: a systematic review

BACKGROUND

Bills have been put forward in the UK and Republic of Ireland proposing a move to Central European Time (CET). Proponents argue that such a change will have benefits for road safety, with daylight being shifted from the morning, when collision risk is lower, to the evening, when risk is higher. Studies examining the impact of daylight saving time (DST) on road traffic collision risk can help inform the debate on the potential road safety benefits of a move to CET. The objective of this systematic review was to examine the impact of DST on collision risk.

METHODS

Major electronic databases were searched, with no restrictions as to date of publication (the last search was performed in January 2017). Access to unpublished reports was requested through an international expert group. Studies that provided a quantitative analysis of the effect of DST on road safety-related outcomes were included. The primary outcomes of interest were road traffic collisions, injuries and fatalities.

FINDINGS

Twenty-four studies met the inclusion criteria. Seventeen examined the short-term impact of transitions around DST and 12 examined long-term effects. Findings from the short-term studies were inconsistent. The long-term findings suggested a positive effect of DST. However, this cannot be attributed solely to DST, as a range of road collision risk factors vary over time.

INTERPRETATION

The evidence from this review cannot support or refute the assertion that a permanent shift in light from morning to evening will have a road safety benefit.

Sleepy Punishers Are Harsh Punishers

The degree of punishment assigned to criminals is of pivotal importance for the maintenance of social order and cooperation. Nonetheless, the amount of punishment assigned to transgressors can be affected by factors other than the content of the transgressions. We propose that sleep deprivation in judges increases the severity of their sentences. We took advantage of the natural quasi-manipulation of sleep deprivation during the shift to daylight saving time in the spring and analyzed archival data from judicial punishment handed out in the U.S. federal courts. The results supported our hypothesis: Judges doled out longer sentences when they were sleep deprived.

Association of daylight saving time transitions with incidence and in-hospital mortality of myocardial infarction in Finland

INTRODUCTION

Circadian rhythm disturbance increases cardiovascular risk but the effects of daylight saving time (DST) transitions on the risk of myocardial infarction (MI) are unclear.

METHODS

We studied association of DST transitions in 2001-2009 with incidence and in-hospital mortality of MI admissions nationwide in Finland. Incidence rations (IR) of observed incidences on seven days following DST transition were compared to expected incidences.

RESULTS

Incidence of MI increased on Wednesday (IR 1.16; CI 1.01-1.34) after spring transition (6298 patients' cohort). After autumn transition (8161 patients' cohort), MI incidence decreased on Monday (IR 0.85; CI 0.74-0.97) but increased on Thursday (IR 1.15; CI 1.02-1.30). The overall incidence of MI during the week after each DST transition did not differ from control weeks. Patient age or gender, type of MI or in-hospital mortality were not associated with transitions. Renal insufficiency was more common among MI patients after spring transition (OR 1.81; CI 1.06-3.09; p < 0.05). Diabetes was less common after spring transition (OR 0.71; CI 0.55-0.91; p = 0.007), but more common after autumn transition (OR 1.21; 1.00-1.46; p < 0.05).

CONCLUSIONS

DST transitions are followed by changes in the temporal pattern but not the overall rate of MI incidence. Comorbidities may modulate the effects DST transitions.

Adverse Effects of Daylight Saving Time on Adolescents' Sleep and Vigilance

STUDY OBJECTIVES

Daylight saving time (DST) has been established with the intent to reduce energy expenditure, however unintentional effects on sleep and vigilance have not been consistently measured. The objective of this study was to test the hypothesis that DST adversely affects high school students' sleep and vigilance on the school days following its implementation.

METHODS

A natural experiment design was used to assess baseline and post-DST differences in objective and subjective measures of sleep and vigilance by actigraphy, sleep diary, sleepiness scale, and psychomotor vigilance testing (PVT). Students were tested during school days immediately preceding and following DST.

RESULTS

A total of 40 high school students were enrolled in this study; 35 completed the protocol. Sleep duration declined by an average of 32 minutes on the weeknights post-DST, reflecting a cumulative sleep loss of 2 h 42 min as compared to the baseline week (p = 0.001). This finding was confirmed by sleep diary analyses, reflecting an average sleep loss of 27 min/night (p = 0.004) post-DST. Vigilance significantly deteriorated, with a decline in PVT performance post-DST, resulting in longer reaction times (p < 0.001) and increased lapses (p < 0.001). Increased daytime sleepiness was also demonstrated (p < 0.001).

CONCLUSION

The early March DST onset adversely affected sleep and vigilance in high school students resulting in increased daytime sleepiness. Larger scale evaluations of sleep impairments related to DST are needed to further quantify this problem in the population. If confirmed, measures to attenuate sleep loss post-DST should be implemented.

Pitfalls of insulin pump clocks: technical glitches that may potentially affect medical care in patients with diabetes

The objective was to raise awareness about the importance of ensuring that insulin pumps internal clocks are set up correctly at all times. This is a very important safety issue because all commercially available insulin pumps are not GPS-enabled (though this is controversial), nor equipped with automatically adjusting internal clocks. Special attention is paid to how basal and bolus dose errors can be introduced by daylight savings time changes, travel across time zones, and am-pm clock errors. Correct setting of insulin pump internal clock is crucial for appropriate insulin delivery. A comprehensive literature review is provided, as are illustrative cases. Incorrect setting can potentially result in incorrect insulin delivery, with potential harmful consequences, if too much or too little insulin is delivered. Daylight saving time changes may not significantly affect basal insulin delivery, given the triviality of the time difference. However, bolus insulin doses can be dramatically affected. Such problems may occur when pump wearers have large variations in their insulin to carb ratio, especially if they forget to change their pump clock in the spring. More worrisome than daylight saving time change is the am-pm clock setting. If this setting is set up incorrectly, both basal rates and bolus doses will be affected. Appropriate insulin delivery through insulin pumps requires correct correlation between dose settings and internal clock time settings. Because insulin pumps are not GPS-enabled or automatically time-adjusting, extra caution should be practiced by patients to ensure correct time settings at all times. Clinicians and diabetes educators should verify the date/time of insulin pumps during patients' visits, and should remind their patients to always verify these settings.