How Hong Kong’s light pollution can ruin your nights and make days a drag

(SCMP)Ifyourneighbourhoodiswelllitatnight,youmaynotbesleepingwell,accordingtonewresearchbyStanfordUniversity.Inastudythatinvolvedabout16,000peopleintheUnitedStatesovereightyears,thescientistsfoundthatnight-timelightaffectssleepdurationandwassignificantlyassociatedwithsleepdisturbances.

Studyparticipantslivinginmoreintenselightareasweremorelikelytobedissatisfiedwiththeirsleepquantityorqualitythanthoselivinginless-intenselightareas,with29percentdissatisfiedcomparedto16percent.

“Ourworldhasbecomea24/7society.Weuseoutdoorlighting,suchastreetlights,tobemoreactiveatnightandtoincreaseoursafetyandsecurity,”saysstudyauthorandsleepmedicineexpertDrMauriceOhayon,aprofessorofpsychiatryandbehaviouralsciencesatStanford.“Theconcernisthatwehavereducedourexposuretodarknessanditcouldbeaffectingoursleep.”

HongKongowesthisreputationinparttoa2013studybyHongKongUniversityscientists,whofoundthecity’surbannightskytobeasmuchas1,000timesbrighterthaninternationalnorms.EvenruralareasinHongKongwereaffected:theWetlandParkinTinShuiWaiwasonaverage100timesbrighterthantheinternationalstandardfornightskiessetbytheInternationalAstronomicalUnion,theHKUstudyfound.

InthenewStanfordstudy,15,863peoplewereinterviewedbyphoneabouttheirsleephabits,qualityofsleepaswellasmedicalandpsychiatricdisorders.Then,withnighttimedatafromtheUSDefenceMeteorologicalSatelliteProgramme,theresearcherslookedathowmuchoutdoorlightthosepeoplewereexposedtoatnight.

Peoplelivinginmoreintenselightareaswere6percentmorelikelytosleeplessthansixhourspernightthanpeopleinlessintenselightareas.Theyweremorelikelytoreportfatiguethanthosewithlowlightexposure-9percentcomparedto7percent.Andtheyalsosleptslightlylesspernightthanthosewithlowlightexposure-anaverageofsixhours,41minutespernightcomparedtosixhours,52minutespernight.

Inaddition,peoplewithhighlightexposureweremorelikelytowakeupconfusedduringthenightthanpeoplewithlowlightexposure,with19percentexperiencingthiscomparedto13percent.Theywerealsomorelikelytohaveexcessivesleepinessandimpairedfunctioning,at6percentcomparedto2percent.

Lightpollutioncanbefoundinanysizeablecityintheworld.Yetexcessiveexposuretolightatnightmayaffecthowwefunctionduringthedayandincreasetherisksofexcessivesleepiness,”saysOhayon.“Ifthisassociationisconfirmedbyotherstudies,peoplemaywanttoconsiderroomdarkeningshades,sleepmasksorotheroptionstoreducetheirexposure.”

Earlierthisyear,avoluntarytwo-yearschemeaimedatalleviatingextremelevelsoflightpollutionwasintroducedinHongKong.UndertheCharteronExternalLighting,whichstartsinApril,organisationswillbeencouragedtoturnoffexternaldecorative,promotionaloradvertisinglightingfrom11pm.Organisationswhomeetcertaincriteriawillreceiveawardsin2017.