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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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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.:+4314016034935
Received:7February2020;Accepted:29February2020;Published:2March2020
Abstract:InEuropeandmanycountriesworldwide,ahalfyearlychangingtimeschemehasbeen
adoptedwiththeaimofoptimizingtheuseofnaturaldaylightduringworkinghoursandsaving
energy.Becausetheexpectedneteconomicbenefitwasnotachieved,thediscussionaboutthe
optimalsolutionhasbeenreopenedwithashiftedfocusonsocialandhealthrelatedconsequences.
Wesetouttoproduceevidenceforthisdiscussionandanalysedtheimpactofdaylightsavingtime
ontotalmortalityofageneralpopulationinatimeseriesstudyondailytotalmortalityfortheyears
1970–2018inthecityofVienna,Austria.DailydeathsweremodelledbyPoissonregression
controllingforseasonalandlongtermtrend,samedayand14dayaveragetemperature,humidity,
anddayofweek.Duringtheweekafterthespringtransitionasignificantincreaseindailytotal
mortalityofabout3%perdaywasobserved.Thiswasnotthecaseduringtheweekafterthefall
transition.TheincreaseindailymortalityasobservedintheweekafterspringDSTtransitionis
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,wehadaninspiringcoffeetablediscussionwithcolleaguesaftertheyhad
publishedascientificletteronthattopic[4].Theyexpressedtheirpreferencefortheimplementation
ofapermanentstandardtimebecauseofthenegativeimpactofalackofmorninglightforthe
circadiansystemandconcomitanttiredness,impairedattention,andperformance.However,there
wasageneralagreementamongusontheassumptionthatendingthebiannualtransitionmightbe
ofhigherrelevancethanthedecisionbetweensummer‐andstandardtime.
Beforeundertakingthisstudy,severaldatabases(PubMed,Cochrane,WebofScience)were
searchedforthetermʺdaylight(/daylight/daylight)savingtime(/DST)ʺ incombinationwith
ʺmortalityʺwithoutlimitations.Anumberofstudieshavebeenretrievedthatinvestigatedtheimpact
ondaylightsavingtimeinspecificpopulationsegmentsorforaspecificcauseofdeath.Veryfew
studiesanalyzedageneralpopulationandtotalmortalityinthiscontext.However,thesestudiesare
basedonshortertimeperiodswithaccordingimpactonstatisticalpower.
Disruptionofdiurnalcyclescouldcompromisethefunctionofvariousorganfunctions,leading
toincreasedmortalityriskslinkedtomanydifferentcauses,renderingallcausemortalitya
reasonableendpoint.WefurtherhypothesizedthatapartoftheimpactofDSTtransitiononmortality
Int.J.Environ.Res.PublicHealth2020,17,16112of5
couldresultfromincreasedtirednesslinkedtoahigherriskofaccidentsandprofessionalmistakes
[5].
Coincidentally,wewereatthattimeinvestigatingtemporalchangesintemperaturemortality
association[6].Forthatstudy,wehadconstructedaPoissonregressionmodelondailyallcause
mortalityfortheyears1970–2018inVienna,Austria.Wedecidedtoutilizethatdatatoinvestigate
theDSTrelatedimpactontotalmortality.
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)
TuesdayFridayafterthespringtransition,(4)Sunday,(5)Monday,and(6)TuesdayFridayafterthe
falltransition.WeincludedTuesdayFridaybeforethespring(7)andthefall(8)transitionasnegative
controlaswellasthesame4daysasin(3),butinthe1970s(9).
Wecalculatedtheriskratiosonthedaysandperiodsmentionedabove(1–9)inatimeseries
studyusingaPoissonmodelcontrollingfortemporaltrend,asinecosinefunction(wavelengthof
365.25days)mimickingastronomicalchangesinastronomicalsunshinedurationandthus
accountingfortheseasonalpatternofmortality[7],dayofweek,samedayrelativehumidity,moving
averageoftemperatureoverthelast14days,andsamedaytemperature(linearandquadraticterm).
Becauseofthemainhypothesisthatthetimebasedgovernmentalregulationofmorninglight
wouldbeariskfactor,controllingfornaturalchangesinsunshinedurationinthemodelisdeemed
thebestapproach.Astronomicalvariationinsunshinedurationisbestmodelledbyanannualsine
cosinefunction.
StatisticalanalyseswereperformedwithSTATA15.1[8].
3.Results
Aswehavereportedinmoredetailinourpreviouspaper[6],onaverage56.4deathsoccurred
perday.Inspiteofagrowingpopulation,theannualnumberofdeathsdeclinedfrom1970until
about2005andthenremainedfairlystable.Dailymortalitydisplayedaclearseasonalpatternwith
highernumbersinwinter.Onlyinthelast10or15yearsalsoasecondpeakinsummerappearedthat
waswellrepresentedinthemodelbythesamedaytemperature.
ThePoissonregressionmodelprovidedagoodfitwithlittleevidenceforresidual
overdispersion.Analternativelyfittednegativebinomialregressionmodelprovidedverysimilar
estimateswithanalphaof0.0053.
Int.J.Environ.Res.PublicHealth2020,17,16113of5
InterestinglyahighermortalityonSundaysatDSTtransitioninfallwasfound,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
TuesdayFridayafterspringtransition1.0281.006;1.0500.012
Sundayafterfalltransition1.0491.003;1.0970.035
Mondayafterfalltransition0.9410.898;0.9850.009
TuesdayFridayafterfalltransition0.9960.974;1.0190.725
TuesdayFridaybeforespringtransition1.0040.983;1.0260.713
TuesdayFridaybeforefalltransition0.9960.974;1.0190.735
SameTuesdayFridayinspringin1970s0.9870.952;1.0240.484
BoldandItalic:p<0.05.
Thelossofonehourinspringhasnoimmediateadverseeffectontotalmortality,butbecause
theSundayinspringisonehourshorterwewouldindeedexpectareductionindailymortalityby
about4%(insteadofonlyabout1%).Gettingupearlierbyonehourinatimewithnoorlittlemorning
daylight,doesindeedincreasemortalityriskintheconsecutivedays(2.8%increaseindailymortality
perdayforTuesdayFriday)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.Acausespecificanalysisofdeathswouldprovidemoredetailedinsightas
eveninthecaseofaccidentsdifferenttypesdisplaydifferentratesofoccurrenceafterDSTtransition
days[15].Yetwehopetocontributetothefierceongoingdiscussion[16]aboutoptimalregulations
fordaylightsavingtimeandartificialtimezones.
ViennaislocatedrathercentrallyintheMiddleEuropeantimezone.Areductioninearly
morningsunlightmightevenaffectmorewesterlyregionsofthattimezonemoreseverely,aswas
shownfortrafficaccidents[17]andevenforcancerrisks[18,19].Evenaminorsleepreductionbyan
averageof19minutescouldleadtoseverehealthconsequencesincludingobesity,diabetes,
cardiovasculardiseases,andbreastcancer[20]withrelevantimpactsonhealthcarecosts.Therefore,
theresultsfromViennamightevenunderestimatethetruehealtheffectsofDSTinotherregions.
5.Conclusions
Int.J.Environ.Res.PublicHealth2020,17,16114of5
Theresultsofourinvestigationclearlyindicatethatregulatorymeasuresontimeschemesdo
haveaquantifiableimpactonmortalityinaffectedpopulations.Thisfactshouldbeconsideredby
policymakersandcouldprobablyprovideanimportantargumentintheongoingdecisionprocess
[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.
References
1. Havranek,T.;Herman,D.;Irsova,Z.DoesDaylightSavingSaveElectricity?AMetaAnalysis.EnergyJ.
2018,39,doi:10.5547/01956574.39.2.thav.
2. Kellogg,R.;Wolff,H.Daylighttimeandenergy:EvidencefromanAustralianexperiment.J.Environ.Econ.
Manag.2008,56,207–220,doi:10.1016/j.jeem.2008.02.003.
3. EuropeanCommission.ProposalforaDirectiveoftheEuropeanParliamentandoftheCouncil
discontinuingseasonalchangesoftimeandrepealingDirective2000/84/EC.COM/2018/639final.2018.
Availableonline:https://eurlex.europa.eu/legalcontent/EN/TXT/HTML/?uri=CELEX:52018PC0639&
from=EN(accessedon16January2020).
4. Ekmekcioglu,C.;Kundi,M.;Hutter,HP.Letthemorningsunshinein.Lancet2019.394,1518.
5. Roenneberg,T.;WirzJustice,A.;Skene,D.J.;AncoliIsrael,S.;Wright,K.P.;Dijk,D.J.;Zee,P.;Gorman,
M.R.;Winnebeck,E.C.;Klerman,E.B.WhyShouldWeAbolishDaylightSavingTime?J.Biol.Rhythms2019,
34,227–230,doi:10.1177/0748730419854197.
6. Weitensfelder,L.;Moshammer,H.Evidenceofadaptationtoincreasingtemperatures.Int.J.Environ.Res.
PublicHealth2019,17,97,doi:10.3390/ijerph17010097
7. Aschoff,J.AnnualRhythmsinMan.InBiologicalRhythmsAschoff,J.Ed.Springer:Boston,MA,1981,pp.
475–487,ISBN9781461565543
8. STATAVers.15.1.StataCorp:CollegeStation,TX,USA,2017.
9. Janszky,I.;Ljung,R.ShiftstoandfromDaylightSavingTimeandIncidenceofMyocardialInfarction.
NEJM,2008,359,1966–1968.
10. Manfredini,R.;Fabbian,F.;Cappadona,R.;DeGiorgi,A.;Bravi,F.;Carradori,T.;Flacco,M.E.;Manzoli,L.
DaylightSavingTimeandAcuteMyocardialInfarction:AMetaAnalysis.J.Clin.Med.2019,8,E404,
doi:10.3390/jcm8030404.
11. Manfredini,R.;Fabbian,F.;DeGiorgi,A.;Cappadona,R.;Capodaglio,G.;Fedeli,U.Daylightsavingtime
transitionsandcirculatorydeaths:datafromtheVenetoregionofItaly.Emerg.Med.J.2019,14,1185–1187,
doi:10.1007/s11739019020855.
12. Lindenberger,L.M.;Ackermann,H.;Parzeller,M.Thecontroversialdebateaboutdaylightsavingtime
(DST)resultsofaretrospectiveforensicautopsystudyinFrankfurt/Main(Germany)over10years(2006–
2015).Int.J.Legal.Med.2019,133,1259–1265,doi:10.1007/s004140181960z.
13. PratsUribe,A.;Tobías.A.;PrietoAlhambra,D.ExcessRiskofFatalRoadTrafficAccidentsontheDayof
DaylightSavingTimeChange.Epidemiology2018,29,e44–e45,doi:10.1097/EDE.0000000000000865.
14. Sipilä,J.O.;Ruuskanen,J.O.;Rautava,P.;Kytö,V.Changesinischemicstrokeoccurrencefollowing
daylightsavingtimetransitions.SleepMed.2016,2728,20–24,doi:10.1016/j.sleep.2016.10.009.
15. Robb,D.;Barnes,T.Accidentratesandtheimpactofdaylightsavingtimetransitions.Accid.Anal.Prev.
2018,111,193–201,doi:10.1016/j.aap.2017.11.029.
16. Roenneberg,T.;Winnebeck,E.C.;Klerman,E.B.DaylightSavingTimeandArtificialTimeZones—ABattle
betweenBiologicalandSocialTimes.Front.Physiol.2019,10,944,doi:10.3389/fphys.2019.00944.
Int.J.Environ.Res.PublicHealth2020,17,16115of5
17. Fritz,J.;VoPham,T.;Wright,K.P.;Vetter,C.AChronobiologicalEvaluationoftheAcuteEffectsofDaylight
SavingTimeonTrafficAccidentRisk.Curr.Boil.2020,30,729–735.e2,
https://doi.org/10.1016/j.cub.2019.12.045.
18. James,P.;Bertrand,K.A.;Hart,J.E.;Schernhammer,E.S.;Tamimi,R.M.;Laden,F.OutdoorLightatNight
andBreastCancerIncidenceintheNurses’HealthStudyII.Environ.HealthPerspect.2017,125,8,
doi:10.1289/EHP935.
19. Gu,F.;Xu,S.;Devesa,S.S.;Zhang,F.;Klerman,E.B.;Graubard,B.I.;Caporaso,N.E.LongitudePositionin
aTimeZoneandCancerRiskintheUnitedStates.CancerEpidemiol.BiomarkersPrev.2017,26,1306–1311,
doi:10.1158/10559965.EPI161029.
20. Giuntella,O.;Mazzonna,F.Sunsettimeandtheeconomiceffectsofsocialjetlag:evidencefromU.S.time
zoneborders.J.HealthEcon.2019,65,210–226,doi:10.1016/j.jhealeco.2019.03.007.
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