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Daylight Saving Time Transitions: Impact on Total Mortality

DOI:10.3390/ijerph17051611
Authors:
Michael Poteser at Medical University of Vienna
Michael Poteser
Hanns Moshammer at Medical University of Vienna
Hanns Moshammer
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Abstract and Figures

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.
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Available via license: CC BY
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Int.J.Environ.Res.PublicHealth2020,17,1611;doi:10.3390/ijerph17051611www.mdpi.com/journal/ijerph
Article
DaylightSavingTimeTransitions:ImpactonTotal
Mortality
MichaelPoteser1andHannsMoshammer1,2,*
1DepartmentofEnvironmentalHealth,CenterforPublicHealth,MedicalUniversityofVienna,
Kinderspitalgasse15,1090Vienna,Austria;michael.poteser@meduniwien.ac.at
2NukusbranchofTashkentPediatricMedicalInstitute,DepartmentofHygiene,230100Nukus,Uzbekistan
*Correspondence:hanns.moshammer@meduniwien.ac.at;Tel.:+43‐1‐40160‐34935
Received:7February2020;Accepted:29February2020;Published:2March2020
Abstract:InEuropeandmanycountriesworldwide,ahalf‐yearlychangingtimeschemehasbeen
adoptedwiththeaimofoptimizingtheuseofnaturaldaylightduringworkinghoursandsaving
energy.Becausetheexpectedneteconomicbenefitwasnotachieved,thediscussionaboutthe
optimalsolutionhasbeenreopenedwithashiftedfocusonsocialandhealthrelatedconsequences.
Wesetouttoproduceevidenceforthisdiscussionandanalysedtheimpactofdaylightsavingtime
ontotalmortalityofageneralpopulationinatimeseriesstudyondailytotalmortalityfortheyears
1970–2018inthecityofVienna,Austria.DailydeathsweremodelledbyPoissonregression
controllingforseasonalandlong‐termtrend,same‐dayand14‐dayaveragetemperature,humidity,
anddayofweek.Duringtheweekafterthespringtransitionasignificantincreaseindailytotal
mortalityofabout3%perdaywasobserved.Thiswasnotthecaseduringtheweekafterthefall
transition.TheincreaseindailymortalityasobservedintheweekafterspringDST‐transitionis
mostlikelycausallylinkedtothechangeintimescheme.
Keywords:daylightsavingtime;morningsunlight;totalmortality;timeseriesstudy
1.Introduction
InEuropeandmanycountriesworldwide,ageneralschemeofdaylightsavingtime(DST)has
beenimplemented.OnanightbetweenSaturdayandSundayinspring,clocksaresetforwardone
hourtotakeadvantageoftheprolongeddaylightwiththemainintentionofsavingenergy.Asthe
expectationsforreducednetenergydemandwerefinallynotmet[1,2],theEuropeanCommission
decidedin2018todiscontinueDSTregulation[3],openingthediscussiononpossiblealternativesin
memberstates.Recently,wehadaninspiringcoffee‐tablediscussionwithcolleaguesaftertheyhad
publishedascientificletteronthattopic[4].Theyexpressedtheirpreferencefortheimplementation
ofapermanentstandardtimebecauseofthenegativeimpactofalackofmorninglightforthe
circadiansystemandconcomitanttiredness,impairedattention,andperformance.However,there
wasageneralagreementamongusontheassumptionthatendingthebi‐annualtransitionmightbe
ofhigherrelevancethanthedecisionbetweensummer‐andstandardtime.
Beforeundertakingthisstudy,severaldatabases(PubMed,Cochrane,WebofScience)were
searchedforthetermʺday‐light(/daylight/daylight)savingtime(/DST)ʺ incombinationwith
ʺmortalityʺwithoutlimitations.Anumberofstudieshavebeenretrievedthatinvestigatedtheimpact
ondaylightsavingtimeinspecificpopulationsegmentsorforaspecificcauseofdeath.Veryfew
studiesanalyzedageneralpopulationandtotalmortalityinthiscontext.However,thesestudiesare
basedonshortertimeperiodswithaccordingimpactonstatisticalpower.
Disruptionofdiurnalcyclescouldcompromisethefunctionofvariousorganfunctions,leading
toincreasedmortalityriskslinkedtomanydifferentcauses,renderingall‐causemortalitya
reasonableendpoint.WefurtherhypothesizedthatapartoftheimpactofDSTtransitiononmortality
Int.J.Environ.Res.PublicHealth2020,17,16112of5
couldresultfromincreasedtirednesslinkedtoahigherriskofaccidentsandprofessionalmistakes
[5].
Coincidentally,wewereatthattimeinvestigatingtemporalchangesintemperature‐mortality‐
association[6].Forthatstudy,wehadconstructedaPoissonregressionmodelondailyall‐cause
mortalityfortheyears1970–2018inVienna,Austria.Wedecidedtoutilizethatdatatoinvestigate
theDST‐relatedimpactontotalmortality.
2.MaterialsandMethods
DSTwasintroducedinAustriain1980.Sincethen,aonehourtransitionwasperformedin
springandinfallbetweenSaturdayandSunday:in1980onApril6andSeptember28,intheyears
1981–1995onthelastSundaysinMarchandSeptember,andsince1996onthelastSundaysinMarch
andOctober.
MortalitydatawereobtainedfromthenationalAustrianStatisticsInstitute(StatistikAustria).
ForeachdeathoccurringinAustriasinceJan1,1970,thefollowinginformationwasprovided:Age
(inyears),sex,dateofdeath,mostrecentplaceofresidence(district),andprimarycauseofdeath.
ThelatterinformationwasprovidedasInternationalCodeofDiagnoses(ICD)version8(ICD8)until
1979,asICD9until2001,andasICD10from2002onward.After2015dataregardingthecauseof
deathwasnolongeravailableduetopersonaldataprotectionconcerns.Becauseofthechangesin
diagnosticcoding,thelackofinformationaboutthecauseofdeathforthelast4yearsandthelackof
ahypothesislinkingaspecificcauseofdeathsingularlytoDST,onlytotaldailymortalitywas
considered,amongthegeneralpopulationofthecityofVienna.
Meteorologicaldata(dailymeantemperatureanddailymeanrelativehumidity)wereabstracted
fromtheannualreportsoftheAustrianMeteorologicalService(ZentralanstaltfürMeteorologieund
Geodynamik,www.zamg.ac.at,sourcerecordingstationʺHoheWarteʺ,westernVienna).
InthecontextofDST,weexpectedimmediateeffectsofasinglehourofsleeplostinspring.
WeekendshiftworkerswouldalreadybeaffectedonSundays,othersonMondaysonly.According
toourcolleagues’theory[4]wewouldnotonlyexpectsuchimmediateoutcomes,butalsomore
prolongedeffectsinducedbyprolongeddarknessinthemorning.Thereforeweinvestigatedthe
followingdaysinrelationtoDST(scheduledat3amonSunday):(1)Sunday,(2)Monday,and(3)
Tuesday‐Fridayafterthespringtransition,(4)Sunday,(5)Monday,and(6)Tuesday‐Fridayafterthe
falltransition.WeincludedTuesday‐Fridaybeforethespring(7)andthefall(8)transitionasnegative
controlaswellasthesame4daysasin(3),butinthe1970s(9).
Wecalculatedtheriskratiosonthedaysandperiodsmentionedabove(1–9)inatimeseries
studyusingaPoissonmodelcontrollingfortemporaltrend,asine‐cosinefunction(wave‐lengthof
365.25days)mimickingastronomicalchangesinastronomicalsunshinedurationandthus
accountingfortheseasonalpatternofmortality[7],dayofweek,same‐dayrelativehumidity,moving
averageoftemperatureoverthelast14days,andsame‐daytemperature(linearandquadraticterm).
Becauseofthemainhypothesisthatthetime‐basedgovernmentalregulationofmorninglight
wouldbeariskfactor,controllingfornaturalchangesinsunshinedurationinthemodelisdeemed
thebestapproach.Astronomicalvariationinsunshinedurationisbestmodelledbyanannualsine‐
cosinefunction.
StatisticalanalyseswereperformedwithSTATA15.1[8].
3.Results
Aswehavereportedinmoredetailinourpreviouspaper[6],onaverage56.4deathsoccurred
perday.Inspiteofagrowingpopulation,theannualnumberofdeathsdeclinedfrom1970until
about2005andthenremainedfairlystable.Dailymortalitydisplayedaclearseasonalpatternwith
highernumbersinwinter.Onlyinthelast10or15yearsalsoasecondpeakinsummerappearedthat
waswellrepresentedinthemodelbythesame‐daytemperature.
ThePoissonregressionmodelprovidedagoodfitwithlittleevidenceforresidual
overdispersion.Analternativelyfittednegativebinomialregressionmodelprovidedverysimilar
estimateswithanalphaof0.0053.
Int.J.Environ.Res.PublicHealth2020,17,16113of5
InterestinglyahighermortalityonSundaysatDST‐transitioninfallwasfound,followedbyan
equallystrongprotectiveeffectonMondays(Table1).Beingabletosleeponehourlongerseems
beneficial,whilethehigherratesonSundaysareconsistentwithanincreasedriskofaccidentsin
peopleengagedinnightandweekendshiftwork.However,theincreaseindeathsonthatSunday
couldalsobeanartefactsimplyduetothefactthatthisdayisonehourlonger.Assumingnoeffect
onhourlymortalityratewewouldexpectanincreaseindailyratesbyabout4%asisindeedthecase.
Table1.Riskratiosbeforeandafterdaylightsavingtime(DST)transitions.
Day(s)RiskRatio(log(B))95%ConfidenceIntervalp
Sundayafterspringtransition0.9910.948;1.0360.686
Mondayafterspringtransition0.9790.938;1.0230.350
Tuesday‐Fridayafterspringtransition1.0281.006;1.0500.012
Sundayafterfalltransition1.0491.003;1.0970.035
Mondayafterfalltransition0.9410.898;0.9850.009
Tuesday‐Fridayafterfalltransition0.9960.974;1.0190.725
Tuesday‐Fridaybeforespringtransition1.0040.983;1.0260.713
Tuesday‐Fridaybeforefalltransition0.9960.974;1.0190.735
SameTuesday‐Fridayinspringin1970s0.9870.952;1.0240.484
BoldandItalic:p<0.05.
Thelossofonehourinspringhasnoimmediateadverseeffectontotalmortality,butbecause
theSundayinspringisonehourshorterwewouldindeedexpectareductionindailymortalityby
about4%(insteadofonlyabout1%).Gettingupearlierbyonehourinatimewithnoorlittlemorning
daylight,doesindeedincreasemortalityriskintheconsecutivedays(2.8%increaseindailymortality
perdayforTuesday‐Friday)aftertheintroductionofthesummertimeinspring.
4.Discussion
Contrarytoourownspontaneoushypothesiswedidnotfindclearevidenceofanimmediate
effectofthetransitionsondaily(orratherhourly)mortalityonSundays.Wedidfindarather
prolongedeffectwithhighermortalityratesintheweekafterthespringtransitionandamuch
weakerandshorter(Mondayonly)beneficialeffectafterthefalltransition.
Ourfindingsareinsupportofthehypothesisofourcolleagues[4]andconsistentwith
previouslyreportedincreasedrisksofmyocardialinfarctionintheweekfollowingthespring
transition[9]oreveninthefollowingtwoweeks[10].Thatsameworkinggroupalsoreportedtheir
ownfindingsregardingcirculatorydeathsfromtheVenetoregioninItaly.Similartoourresults,they
foundnoincreaseincirculatorydeathsontheMondaysafterthespringtransitionbutonthe
followingdays(withasignificantincreaseonTuesday)[11].Incontrasttoourfindings,theirmeta‐
analysis[10]alsoshowedahigherincidenceintheweeksfollowingthefalltransition.Lindenberger
etal.[12]foundmortalityduetovariouscausesofdeathincreasedafterthespringbutnotthefall
transition.Ourexpectationofincreasedrisksdirectlyafterthetransition[9,13,14]wasonlypartly
confirmedbyourdata.Acause‐specificanalysisofdeathswouldprovidemoredetailedinsightas
eveninthecaseofaccidentsdifferenttypesdisplaydifferentratesofoccurrenceafterDSTtransition
days[15].Yetwehopetocontributetothefierceon‐goingdiscussion[16]aboutoptimalregulations
fordaylightsavingtimeandartificialtimezones.
ViennaislocatedrathercentrallyintheMiddle‐Europeantimezone.Areductioninearly
morningsunlightmightevenaffectmorewesterlyregionsofthattimezonemoreseverely,aswas
shownfortrafficaccidents[17]andevenforcancerrisks[18,19].Evenaminorsleepreductionbyan
averageof19minutescouldleadtoseverehealthconsequencesincludingobesity,diabetes,
cardiovasculardiseases,andbreastcancer[20]withrelevantimpactsonhealth‐carecosts.Therefore,
theresultsfromViennamightevenunderestimatethetruehealtheffectsofDSTinotherregions.
5.Conclusions
Int.J.Environ.Res.PublicHealth2020,17,16114of5
Theresultsofourinvestigationclearlyindicatethatregulatorymeasuresontimeschemesdo
haveaquantifiableimpactonmortalityinaffectedpopulations.Thisfactshouldbeconsideredby
policymakersandcouldprobablyprovideanimportantargumentintheon‐goingdecisionprocess
[3]foranoptimalgeneraltimescheme.
Thisstudyisthefirstprovidingevidenceforgeneralpublichealthoutcomesofdaylightsaving
timetransitionsbasedonmultipledecadeobservations.Usingtotalmortalityasanegativeindicator
fortheimpactonpublichealth,wedemonstratethattransitionperiodsindaylightsavingtime
regulationsarelinkedtoariseintotalmortalityandshouldbeavoidedintheinterestofgeneralwell‐
being.
AuthorContributions:Conceptualization,H.M.andM.P.;methodology,H.M.;formalanalysis,H.M.;writing—
originaldraftpreparation,M.P.;writing—reviewandediting,H.M.andM.P.Allauthorshavereadandagreed
tothepublishedversionofthemanuscript.
Funding:Thisresearchreceivednoexternalfunding.
ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.
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©2020bytheauthors.LicenseeMDPI,Basel,Switzerland.Thisarticleisanopenaccess
articledistributedunderthetermsandconditionsoftheCreativeCommonsAttribution
(CCBY)license(http://creativecommons.org/licenses/by/4.0/).
... Spring transitions were found to be associated with a shift in onset as well as a modestly increased risk of myocardial infarction (MI) 7,[9][10][11][12][13][14][15][16] , ischaemic stroke (IS) 17,18 , motor vehicle accidents (MVAs) [19][20][21] , atrial fibrillation (AF) 22 , patient safetyrelated incidents (SRIs) 23 and suicides 24,25 . Because these conditions represent a high proportion of general mortality, it was hypothesised that DST could impinge on general mortality patterns 26 . ...
... week 1; +2.3% week 2 post-DST). They are in striking contrast to the general scientific postulate that has driven much of the DST literature (i.e. a minimal deprivation of sleep would result in an increase in mortality) and to the conclusions of previous papers which emphasised the question of mortality 14,25,26 . ...
... One of them, whose methodology is somewhat comparable to this study, assesses the effects of DST on general mortality in the city of Vienna between 1970 and 2018, using a Poisson regression model 26 . It finds an increase in mortality of about 3% per day in the week following DST in spring (Tuesday to Friday) and an apparent weak protective role of Monday after the transition in fall. ...
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Daylight saving time (DST) consists in a one-hour advancement of legal time in spring offset by a backward transition of the same magnitude in fall. It creates a minimal circadian misalignment that could disrupt sleep and homoeostasis in susceptible individuals and lead to an increased incidence of pathologies and accidents during the weeks immediately following both transitions. How this shift affects mortality dynamics on a large population scale remains, however, unknown. This study examines the impact of DST on all-cause mortality in 16 European countries for the period 1998-2012. It shows that mortality decreases in spring and increases in fall during the first two weeks following each DST transition. Moreover, the alignment of time data around DST transition dates revealed a septadian mortality pattern (lowest on Sundays, highest on Mondays) that persists all-year round, irrespective of seasonal variations, in men and women aged above 40. How daylight saving time shift (DST) affects mortality dynamics on a large population scale remains unknown. Here, the authors examine the impact of DST on all-cause mortality in 16 European countries for the period 1998-2012.
View
... 12 Similarly, a daily 3% increase in the incidence of all-cause mortality has also been reported following the spring DST transition. 13 As a result, some authors have advocated for the removal of DST. 12 Acute cardiovascular events follow diurnal patterns with the majority of AMI and OHCA occurring between 6am and noon. 7 As the majority of fatal AMI events occur outside of hospital, 14 it is unclear if an increased risk of AMI with DST transitions also translates into an increased risk of OHCA. ...
... 17 In comparison, an Austrian study investigating national all-cause mortality data reported a 3% increased risk of mortality for each individual day in the week following the spring DST transition. 13 A study of atrial fibrillation hospitalisations following DST transitions reported a significant increase in hospitalisation in the week following the spring DST transition. 10 A possible explanation for the harm associated by the spring DST transition is the physiological effects caused by a reduction in sleep opportunity. ...
... Contrary to other work investigating the effect of DST transitions on acute cardiovascular events, our findings show both potentially harmful and protective effects from DST transitions. 12,13 A transient increase in the risk of OHCA during the spring DST transition appears to be entirely offset by a concomitant reduction in the risk of OHCA during autumn. However, our findings may provide an opportunity to target at-risk groups with preventive strategies. ...
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Background: Many studies have reported increases in the risk of acute cardiovascular events following daylight savings time (DST) transitions. We sought to investigate the effect of DST transition on the incidence of out-of-hospital cardiac arrest (OHCA). Methods: Between January 2000 and December 2020, we performed an interrupted time series analysis of the daily number of OHCA cases of medical aetiology from the Victorian Ambulance Cardiac Arrest Registry. The effect of DST transition on OHCA incidence was estimated using negative binomial models, adjusted for temporal trends, population growth, and public holidays. Results: A total of 89,409 adult OHCA of medical aetiology were included. Following the spring DST transition (i.e. shorter day), there was an immediate 13% (IRR 1.13, 95% CI: 1.02, 1.25; p=0.02) increased risk of OHCA on the day of transition (Sunday) and the cumulative risk of OHCA remained higher over the first 2 days (IRR 1.17, 95% CI: 1.02, 1.34; p=0.03) compared to non-transitional days. Following the autumn DST transition (i.e. longer day), there was a significant lagged effect on the Tuesday with a 12% (IRR 0.88, 95% CI: 0.77, 0.99; p=0.04) reduced risk of OHCA. The cumulative effect following the autumn DST transition was also significant, with a 30% (IRR 0.70, 95% CI: 0.51, 0.96; p=0.03) reduction in the incidence of OHCA by the end of the transitional week. Conclusion: We observed both harmful and protective effects from DST transitions on the risk of OHCA. Strategies to reduce this risk in vulnerable populations should be considered.
View
... Havranek et al. [1] surveyed 162 estimates from 44 studies and found that the mean reported impact indicated only slight electricity savings (0.34%) during the days when DST was applied, with the electricity savings increasing in countries that are located farther away from the equator. The abrupt change in the timing of daily activities on the days of DST clock change has been shown to result in different health effects, e.g., increased rate of acute myocardial infarction [2], increased daily mortality [3], and excess risk of fatal road accidents [4]. On the other hand, positive health effects/benefits were reported due to increased time for leisure activities in the summer evenings [5]. ...
... Similarly, during the day dispersion processes are very efficient due to the atmospheric boundary layer (ABL) instability, which is usually accompanied by vigorous winds, turbulence and photochemical reactions. Generally, these conditions result in suppression of concentrations of primary pollutants, e.g., NOx [6][7][8], and increase in the formation of secondary pollutants, e.g., O 3 . In contrast, the strong nocturnal atmospheric stability, weaker winds, low turbulence and lack of photochemical reactions promote buildup of high concentrations of primary pollutants and of their oxidation produces the night. ...
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Implementation of Daylight Savings Time (DST) started in various jurisdictions during the first half of the 20th century. Much debate on the merits of the twice-yearly change in the official local time has ensued since then regarding energy usage, sleep patterns, health outcomes, traffic safety, etc. The DST switch in the official time abruptly shifts anthropogenic emissions that are related to human activities relative to the Coordinated Universal Time (UTC) but does not affect meteorological processes that disperse them, which day-to-day variability is affected by longer time scales. Here, we utilized the DST clock changes as a repeating biannual experiment to study the impact of meteorology on air pollution. We analyzed traffic volume data and up to 20 years of nitrogen oxides (NOx), fine particulate matter (PM2.5), ozone (O3) and carbon monoxide (CO) concentrations, observed at different air quality monitoring (AQM) stations in Israel, demonstrating a clear and significant impact of the daily meteorological cycle on traffic related air pollution (TRAP). In particular, traffic emissions are prerequisite for TRAP, but meteorology was found to dominate the daily patterns of the NOx, O3 and CO concentration fields in the study area. On the other hand, the impact of vehicle emissions on PM2.5 concentrations seems to be very small. Our results highlight the multiscale interplay between pollutant emissions and dispersion processes, especially for pollutants that are emitted near the surface. We demonstrate that while DST clock changes do not affect the emissions intensity, nor the meteorological processes vigor, they do shift human activity-related emissions with respect to the DST-blind dispersion processes. This results in short-term effects on primary traffic-related pollutant concentrations that cancel out over the day, and a consistent yet small effect on secondary traffic-related pollutant concentrations (O3).
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... Daylight Saving Time (DST) transitions also represent discrete events altering regular scheduling due to the resetting of clocks. The transition of moving clocks forward by 1 h for DST in the spring reportedly contributes to shortened sleep and is associated with increased motor vehicle crashes, workplace injuries, heart attacks, and allcause mortality (Barnes and Wagner, 2009;Sandhu et al., 2014;Manfredini et al., 2019;Fritz et al., 2020;Poteser and Moshammer, 2020). However, changes to both sleep and alcohol use on specific holidays over the course of a year have not been comprehensively characterized. ...
... Additional research on the public health effects of such marked, acute changes in sleep patterns and alcohol use would help to elucidate the implications of a combination of changes that have been associated with improvements to health (e.g., increased sleep duration) and challenges to health (e.g., delayed sleep timing, increased alcohol use). For example, as described in the Introduction, DST transitions have been researched extensively, providing evidence that the Spring Ahead DST transition is associated with increased motor vehicle crashes, workplace injuries, heart attacks, and all-cause mortality (Barnes and Wagner, 2009;Sandhu et al., 2014;Manfredini et al., 2019;Fritz et al., 2020;Poteser and Moshammer, 2020). Holidays do not present the same acute perturbation of the timing of environmental light-dark cycles as DST transitions, though comparatively larger changes to sleep and alcohol use patterns were observed on several holidays (especially the days of and before Thanksgiving, Christmas, and New Year's), suggesting the need for future research to investigate the impact of these changes on health. ...
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Full-text available
  • Jul 2022
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.
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... A more rapid adjustment is also reached by the variable (TiMo) with a less endogenous component [1,45,48]. In any case, both transitions to DST and back to ST have effects on circadian variables, corroborating that, in terms of circadian synchronization, DST should be abolished in favor of permanent ST since it matches the sun time more accurately and, therefore, it is more respectful of our internal rhythms [4,[68][69][70][71]. ...
Phase Response Curve to Light under Ambulatory Conditions: A Pilot Study for Potential Application to Daylight Saving Time Transitions
Article
Full-text available
  • Oct 2022
Several studies have investigated the relationship between daylight saving time (DST) and sleep alterations, psychiatric disorders, cardiovascular events and traffic accidents. However, very few have monitored participants while maintaining their usual lifestyle before and after DST. Considering that DST transitions modify human behavior and, therefore, people’s light exposure patterns, the aim of this study was to investigate the potential effects of DST on circadian variables, considering sleep and, for the first time, the human phase response curve to light. To accomplish this, eight healthy adults (33 ± 11 years old, mean ± SD) were recruited to monitor multivariable circadian markers and light exposure by means of a wearable ambulatory monitoring device: Kronowise®. The following night phase markers were calculated: midpoints of the five consecutive hours of maximum wrist temperature (TM5) and the five consecutive hours of minimum time in movement (TL5), sleep onset and offset, as well as sleep duration and light intensity. TM5 for wrist temperature was set as circadian time 0 h, and the balance between advances and delays considering the phase response curve to light was calculated individually before and after both DST transitions. To assess internal desynchronization, the possible shift in TM5 for wrist temperature and TL5 for time in movement were compared. Our results indicate that the transition to DST seems to force the circadian system to produce a phase advance to adapt to the new time. However, the synchronizing signals provided by natural and personal light exposure are not in line with such an advance, which results in internal desynchronization and the need for longer synchronization times. On the contrary, the transition back to ST, which implies a phase delay, is characterized by a faster adaptation and maintenance of internal synchronization, despite the fact that exposure to natural light would favor a phase advance. Considering the pilot nature of this study, further research is needed with higher sample sizes.
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... The Spring transition to Daylight Saving Time (DST) has been associated with an increase in overall mortality (Poteser and Moshammer, 2020) and higher autopsy rates (Lindenberger et al., 2019). As most forms of desynchrony between the endogenous circadian clock and the natural environment, DST has been associated with unfavorable health outcomes, including reduced sleep duration and impaired sleep quality (Lahti et al., 2006;Rishi et al., 2020), cardiovascular accidents (Janszky et al., 2012;Janszky and Ljung, 2008;Kirchberger et al., 2015) and the likelihood of reaccessing Accident & Emergency services within 96 h of a first visit (Ferrazzi et al., 2018). ...
Driving simulator performance worsens after the Spring transition to Daylight Saving Time
Article
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  • Jun 2022
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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Chronobiology: Is daylight saving time a deer saving time?
Article
Earlier human activity relative to sunrise and sunset, the very essence of daylight saving time, is linked with health and safety detriments in humans. A new study predicts that deer, at least, may benefit from earlier human activity through reduced deer–vehicle collisions.
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Application of an Electronic Health Record System for Studying the Influence of the Daylight-Saving Time Change on Health Needs
Article
  • Oct 2021
Daylight-Saving Time (DST) was introduced in Bulgaria on April 1st, 1979. Since 1997, DST begins at 3 a.m. on the last Sunday in March and lasts until 3 a.m. on the last Sunday in October. In 1999, daylight saving time began at 3 a.m. on the last Sunday in March and lasted until 4 a.m. on the last Sunday in October. The original idea of daylight-saving time was focused on saving electricity and using the light part of the day, but as a more serious argument at the moment is the impact of time change on the health of citizens, MEPs decided to stop this practice in 2021 [1] The paper presents data from an Electronic Health Record system (EHR), developed for Central Emergency Help Services in Sofia Municipality, which stores each emergency call on the territory of the district, and for the purposes of the study data were studied and processed as follows: number of emergency calls 1 week before the time change, the week after the time change and one additional week for a two-year period of the system‘s operation. The results showed an increase of the number of emergency calls on all the days of the first week with a peak on the first and last working days and a decrease in the second week regardless of the season. The results support the decision to cancel the time change due to the fact that it affects the health status of people negatively.
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A chronobiological evaluation of the risks of cancelling Daylight Saving Time
Article
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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 20th century and the exposition to the hours of the dawn 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.
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Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis
Article
Full-text available
  • Mar 2019
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.
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Evidence of Adaptation to Increasing Temperatures
Article
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In times of rising temperatures, the question arises on how the human body adapts. When assumed that changing climate leads to adaptation, time series analysis should reveal a shift in optimal temperatures. The city of Vienna is especially affected by climate change due to its location in the Alpine Range in Middle Europe. Based on mortality data, we calculated shifts in optimal temperature for a time period of 49 years in Vienna with Poisson regression models. Results show a shift in optimal temperature, with optimal temperature increasing more than average temperature. Hence, results clearly show an adaptation process, with more adaptation to warmer than colder temperatures. Nevertheless, some age groups remain more vulnerable than others and less able to adapt. Further research focusing on vulnerable groups should be encouraged.
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Why Should We Abolish Daylight Saving Time?
Article
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Local and national governments around the world are currently considering the elimination of the annual switch to and from Daylight Saving Time (DST). As an international organization of scientists dedicated to studying circadian and other biological rhythms, the Society for Research on Biological Rhythms (SRBR) engaged experts in the field to write a Position Paper on the consequences of choosing to live on DST or Standard Time (ST). The authors take the position that, based on comparisons of large populations living in DST or ST or on western versus eastern edges of time zones, the advantages of permanent ST outweigh switching to DST annu- ally or permanently. Four peer reviewers provided expert critiques of the initial submission, and the SRBR Executive Board approved the revised manuscript as a Position Paper to help educate the public in their evaluation of current legislative actions to end DST.
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Daylight Saving Time and Artificial Time Zones – A Battle Between Biological and Social Times
Article
Full-text available
  • Aug 2019
Many regions and countries are reconsidering their use of Daylight Saving Time (DST) but their approaches differ. Some, like Japan, that have not used DST over the past decades are thinking about introducing this twice-a-year change in clock time, while others want to abolish the switch between DST and Standard Time, but don’t agree which to use: California has proposed keeping perennial DST (i.e., all year round), and the EU debates between perennial Standard Time and perennial DST. Related to the discussion about DST is the discussion to which time zone a country, state or region should belong: the state of Massachusetts in the United States is considering switching to Atlantic Standard Time, i.e., moving the timing of its social clock (local time) 1 h further east (which is equivalent to perennial DST), and Spain is considering leaving the Central European Time to join Greenwich Mean Time (GMT), i.e., moving its social timing 1 h further west. A wave of DST discussions seems to periodically sweep across the world. Although DST has always been a political issue, we need to discuss the biology associated with these decisions because the circadian clock plays a crucial role in how the outcome of these discussions potentially impacts our health and performance. Here, we give the necessary background to understand how the circadian clock, the social clock, the sun clock, time zones, and DST interact. We address numerous fallacies that are propagated by lay people, politicians, and scientists, and we make suggestions of how problems associated with DST and time-zones can be solved based on circadian biology.
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The controversial debate about daylight saving time (DST)—results of a retrospective forensic autopsy study in Frankfurt/Main (Germany) over 10 years (2006–2015)
Article
Full-text available
Worldwide, many people are exposed to biannual time changes. The benefit of Daylight Saving Time (DST) is controversially discussed and its impact on human health is largely unknown. The present study examines, whether effects of these time changes are seen in a forensic autopsy database. The mortality study is based on autopsy protocols provided by the Institute of Legal Medicine, University Clinic of the Goethe-University Frankfurt/Main, covering a period of 10 years (2006–2015). Data regarding mode and cause of death, age, and gender were evaluated for 4 weeks around the transition to and from DST in spring and autumn. A significant (p = 0.04) elevation in the number of autopsies was observed in the first week following the switch to DST in spring, but no significant changes were noted in autumn. Gender-specific analysis indicated that the autopsy rate of females showed a significant (p = 0.01) peak in the first and a decline (p = 0.05) in the second week following the switch to DST. Differences in non-natural death cases primarily included traffic accidents and suicides, in natural death cases fatal cardiac diseases like cardiac insufficiency and acute myocardial infarction. The number of suicides was low (p = 0.05) before, but high (p = 0.07) in the weeks after the introduction of DST. The present evaluation confirmed a potential effect of DST, such as a significant higher autopsy rate in spring during the first week after the introduction to DST. Moreover, a relation between the introduction to DST in spring and an increase in suicide cases was observed.
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A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk
Article
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.
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Sunset Time and the Economic Effects of Social Jetlag Evidence from US Time Zone Borders
Article
The rapid evolution into a 24 h society challenges individuals’ ability to conciliate work schedules and biological needs. Epidemiological research suggests that social and biological time are increasingly drifting apart (“social jetlag”). This study uses a spatial regression discontinuity design to estimate the economic cost of the misalignment between social and biological rhythms arising at the border of a time-zone in the presence of relatively rigid social schedules (e.g., work and school schedules). Exploiting the discontinuity in the timing of natural light at a time-zone boundary, we find that an extra hour of natural light in the evening reduces sleep duration by an average of 19 minutes and increases the likelihood of reporting insufficient sleep. Using data drawn from the Centers for Disease Control and Prevention and the US Census, we find that the discontinuity in the timing of natural light has significant effects on health outcomes typically associated with circadian rhythms disruptions (e.g., obesity, diabetes, cardiovascular diseases, and breast cancer)and economic performance (per capita income). We provide a lower bound estimate of the health care costs and productivity losses associated with these effects.
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