TED英语演讲稿：我们为什么要睡觉

TED你又了解多少?睡眠专家RussellFoster为我们解答为什么要睡觉，以及 WhatI'dliketodotodayistalkaboutoneofmyfavoritesubjects,andthatistheneuroscienceof Now,thereisasound--(Alarmclock)--aah,itworked--asoundthatisdesperately,desperatelyfamiliartomostofus,andofcourseit'sthesoundofthealarmclock.Andwhatthattrulyghastly,awfulsounddoesisstopthesinglemostimportantbehavioralexperiencethatwehave,andthat'ssleep.Ifyou'reanaveragesortofperson,36percentofyourlifewillbespentasleep,whichmeansthatifyouliveto90,then32yearswillhavebeenspententirelyasleep. Nowwhatthat32yearsistellingusisthatsleepatsomelevelisimportant.Andyet,formostofus,wedon'tgivesleepasecondthought.Wethrowitaway.Wereallyjustdon'tthinkaboutsleep.AndsowhatI'dliketodotodayischangeyourviews,changeyourideasandyourthoughtsaboutsleep.AndthejourneythatIwanttotakeyouon,weneedtostartbygoingbackin "Enjoythehoney-heavydewofslumber."Anyideaswhosaidthat?Shakespeare'sJuliusCaesar.Yes,letmegiveyouafewmorequotes."Osleep,Ogentlesleep,nature'ssoftnurse,howhaveIfrightedthee?"Shakespeareagain,from--Iwon'tsayit--theScottishplay.[Correction:HenryIV,Part2](Laughter)Fromthesametime:"Sleepisthegoldenchainthattieshealthandourbodiestogether."Extremelyprophetic,byThomasDekker,anotherElizabethandramatist. Butifwejumpforward400years,thetoneaboutsleepchangessomewhat.ThisisfromThomasEdison,fromthebeginningofthe20thcentury."Sleepisacriminalwasteoftimeandaheritagefromourcavedays."Bang.(Laughter)Andifwealsojumpintothe1980s,someofyoumayrememberthatMargaretThatcherwasreportedtohavesaid,"Sleepisforwimps."Andofcoursetheinfamous--whatwashisname?--theinfamousGordonGekkofrom"WallStreet"said,"Moneyneversleeps." Whatdowedointhe20thcenturyaboutsleep?Well,ofcourse,weuseThomasEdison'slightbulbtoinvadethenight,andweoccupiedthedark,andintheprocessofthisoccupation,we'vetreatedsleepasanillness,almost.We'vetreateditasanenemy.Atmostnow,Isuppose,wetoleratetheneedforsleep,andatworstperhapsmanyofusthinkofsleepasanillnessthatneedssomesortofacure.Andourignoranceaboutsleepisreallyquiteprofound. Whyisit?Whydoweabandonsleepinourthoughts?Well,it'sbecauseyoudon'tdoanythingmuchwhileyou'reasleep,itseems.Youdon'teat.Youdon'tdrink.Andyoudon'thavesex.Well,mostofusanyway.Andsothereforeit's--Sorry.It'sacompletewasteoftime,right?Wrong.Actually,sleepisanincrediblyimportantpartofourbiology,andneuroscientistsarebeginningtoexplainwhyit'ssoveryimportant.Solet'smovetothe Now,herewehaveabrain.Thisisdonatedbyasocialscientist,andtheysaidtheydidn'tknowwhatitwas,orindeedhowtouseit,so--(Laughter)Sorry.SoIborrowedit.Idon'tthinktheynoticed.Okay.(Laughter) ThepointI'mtryingtomakeisthatwhenyou'reasleep,thisthingdoesn'tshutdown.Infact,someareasofthebrainareactuallymoreactiveduringthesleepstatethanduringthewakestate.Theotherthingthat'sreallyimportantaboutsleepisthatitdoesn'tarisefromasinglestructurewithinthebrain,butistosomeextentanetworkproperty,andifweflipthebrainonitsback--Ilovethislittlebitofspinalcordhere--thisbithereisthehypothalamus,andrightunderthereisawholeraftofinterestingstructures,notleastthebiologicalclock.Thebiologicalclocktellsuswhenit'sgoodtobeup,whenit'sgoodtobeasleep,andwhatthatstructuredoesisinteractwithawholeraftofotherareaswithinthehypothalamus,thelateralhypothalamus,theventrolateralpreopticnuclei.Allofthosecombine,andtheysendprojectionsdowntothebrainstemhere.Thebrainstemthenprojectsforwardandbathesthecortex,thiswonderfullywrinklybitoverhere,withneurotransmittersthatkeepusawakeandessentiallyprovideuswithourconsciousness.Sosleeparisesfromawholeraftofdifferentinteractionswithinthebrain,andessentially,sleepisturnedonandoffasaresultofarangeof Okay.Sowherehavewegotto?We'vesaidthatsleepiscomplicatedandittakes32yearsofourlife.ButwhatIhaven'texplainediswhatsleepisabout.Sowhydowesleep?Anditwon'tsurpriseanyofyouthat,ofcourse,thescientists,wedon'thaveaconsensus.Therearedozensofdifferentideasaboutwhywesleep,andI'mgoingtooutlinethreeofthose. Thefirstissortoftherestorationidea,andit'ssomewhatintuitive.Essentially,allthestuffwe'veburnedupduringtheday,werestore,wereplace,werebuildduringthenight.Andindeed,asanexplanation,itgoesbacktoAristotle,sothat's,what,2,300yearsago.It'sgoneinandoutoffashion.It'sfashionableatthemomentbecausewhat'sbeenshownisthatwithinthebrain,awholeraftofgeneshavebeenshowntobeturnedononlyduringsleep,andthosegenesareassociatedwithrestorationandmetabolicpathways.Sothere'sgoodevidenceforthewholerestoration Whataboutenergyconservation?Again,perhapsintuitive.Youessentiallysleeptosavecalories.Now,whenyoudothesums,though,itdoesn'treallypanout.Ifyoucompareanindividualwhohassleptatnight,orstayedawakeandhasn'tmovedverymuch,theenergysavingofsleepingisabout110caloriesanight.Now,that'stheequivalentofahotdogbun.Now,Iwouldsaythatahotdogbuniskindofameagerreturnforsuchacomplicatedanddemandingbehaviorassleep.SoI'mlessconvincedbytheenergyconservationidea. ButthethirdideaI'mquiteattractedto,whichisbrainprocessingandmemoryconsolidation.Whatweknowisthat,ifafteryou'vetriedtolearnatask,andyousleep-depriveindividuals,theabilitytolearnthattaskissmashed.It'sreallyhugelyattenuated.Sosleepandmemoryconsolidationisalsoveryimportant.However,it'snotjustthelayingdownofmemoryandrecallingit.What'sturnedouttobereallyexcitingisthatourabilitytocomeupwithnovelsolutionstocomplexproblemsishugelyenhancedbyanightofsleep.Infact,it'sbeenestimatedtogiveusathreefoldadvantage.Sleepingatnightenhancesourcreativity.Andwhatseemstobegoingonisthat,inthebrain,thoseneuralconnectionsthatareimportant,thosesynapticconnectionsthatareimportant,arelinkedandstrengthened,whilethosethatarelessimportanttendtofadeawayandbelessimportant. Okay.Sowe'vehadthreeexplanationsforwhywemightsleep,andIthinktheimportantthingtorealizeisthatthedetailswillvary,andit'sprobablewesleepformultipledifferentreasons.Butsleepisnotanindulgence.It'snotsomesortofthingthatwecantakeonboardrathercasually.Ithinkthatsleepwasoncelikenedtoanupgradefromeconomytobusinessclass,youknow,theequiavlentof.It'snotevenanupgradefromeconomytofirstclass.Thecriticalthingtorealizeisthatifyoudon'tsleep,youdon'tfly.Essentially,younevergetthere,andwhat'sextraordinaryaboutmuchofoursocietythesedaysisthatwearedesperatelysleep-deprived. Solet'snowlookatsleepdeprivation.Hugesectorsofsocietyaresleep-deprived,andlet'slookatoursleep-o-meter.Sointhe1950s,gooddatasuggeststhatmostofusweregettingaroundabouteighthoursofsleepanight.Nowadays,wesleeponeandahalftotwohourslesseverynight,sowe'reinthesix-and-a-half-hours-every-nightleague.Forteenagers,it'sworse,muchworse.Theyneedninehoursforfullbrainperformance,andmanyofthem,onaschoolnight,areonlygettingfivehoursofsleep.It'ssimplynotenough.Ifwethinkaboutothersectorsofsociety,theaged,ifyouareaged,thenyourabilitytosleepinasingleblockissomewhatdisrupted,andmanysleep,again,lessthanfivehoursanight.Shiftwork.Shiftworkisextraordinary,perhaps20percentoftheworkingpopulation,andthebodyclockdoesnotshifttothedemandsofworkingatnight.It'slockedontothesamelight-darkcycleastherestofus.Sowhenthepooroldshiftworkerisgoinghometotryandsleepduringtheday,desperatelytired,thebodyclockissaying,"Wakeup.isthetimetobeawake."Sothequalityofsleepthatyougetasanightshiftworkerisusuallyverypoor,againinthatsortoffive-hourregion.Andthen,ofcourse,tensofmillionsofpeoplesufferfromjetlag.Sowhoherehasjetlag?Well,mygoodnessgracious.Well,thankyouverymuchindeedfornotfallingasleep,becausethat'swhatyourbrainiscraving.Oneofthethingsthatthebraindoesisindulgeinmicro-sleeps,thisinvoluntaryfallingasleep,andyouhaveessentiallynocontroloverit.Now,micro-sleepscanbesortofsomewhatembarrassing,buttheycanalsobedeadly.It'sbeenestimatedthat31percentofdriverswillfallasleepatthewheelatleastonceintheirlife,andintheU.S.,thestatisticsareprettygood:100,000accidentsonthefreewayhavebeenassociatedwithtiredness,lossofvigilance,andfallingasleep.Ahundredthousandayear.It'sextraordinary.Atanotherlevelofterror,wedipintothetragicaccidentsatChernobylandindeedthespaceshuttleChallenger,whichwassotragicallylost.Andintheinvestigationsthatfollowedthosedisasters,poorjudgmentasaresultofextendedshiftworkandlossofvigilanceandtirednesswasattributedtoabigchunkofthosedisasters. Sowhenyou'retired,andyoulacksleep,youhavepoormemory,youhavepoorcreativity,youhaveincreasedimpulsiveness,andyouhaveoverallpoorjudgment.Butmyfriends,it'ssomuchworsethanthat. youareatiredbrain,thebrainiscravingthingstowakeitup.Sodrugs,stimulants.CaffeinerepresentsthestimulantofchoiceacrossmuchoftheWesternworld.Muchofthedayisfueledbycaffeine,andifyou'reareallynaughtytiredbrain,nicotine.Andofcourse,you'refuelingthewakingstatewiththesestimulants,andthenofcourseitgetsto11o'clockatnight,andthebrainsaystoitself,"Ah,wellactually,Ineedtobeasleepfairlyshortly.WhatdowedoaboutthatwhenI'mfeelingcompletelywired?"Well,ofcourse,youthenresorttoalcohol.Nowalcohol,short-term,youknow,onceortwice,tousetomildlysedateyou,canbeveryuseful.Itcanactuallyeasethesleeptransition.Butwhatyoumustbesoawareofisthatalcoholdoesn'tprovidesleep,abiologicalmimicforsleep.Itsedatesyou.Soitactuallyharmssomeoftheneuralproccessingthat'sgoingonduringmemoryconsolidationandmemoryrecall.Soit'sashort-termacutemeasure,butforgoodnesssake,don'tbecomeaddictedtoalcoholasawayofgettingtosleepeverynight. Anotherconnectionbetweenlossofsleepisweightgain.Ifyousleeparoundaboutfivehoursorlesseverynight,thenyouhavea50percentlikelihoodofbeingobese.What'stheconnectionhere?Well,sleeplossseemstogiverisetothereleaseofthehormoneghrelin,thehungerhormone.Ghrelinisreleased.Itgetstothebrain.Thebrainsays,"Ineedcarbohydrates,"andwhatitdoesisseekoutcarbohydratesandparticularlysugars.Sothere'salinkbetweentirednessandthemetabolicpredispositionforweightgain.Stress.Tiredpeoplearemassivelystressed.Andoneofthethingsofstress,ofcourse,islossofmemory,whichiswhatIsortofjustthenhadalittlelapseof.Butstressissomuchmore.Soifyou'reacutelystressed,notagreatproblem,butit'ssustainedstressassociatedwithsleeplossthat'stheproblem.Sosustainedstressleadstosuppressedimmunity,andsotiredpeopletendtohavehigherratesofoverallinfection,andthere'ssomeverygoodstudiesshowingthatshiftworkers,forexample,havehigherratesofcancer.Increasedlevelsofstressthrowglucoseintothecirculation.Glucosebecomesadominantpartofthevasculatureandessentiallyyoubecomeglucoseintolerant.Therefore,diabetes2.Stressincreasescardiovasculardiseaseasaresultofraisingbloodpressure.Sothere'sawholeraftofthingsassociatedwithsleeplossthataremorethanjustamildlyimpairedbrain,whichiswhereIthinkmostpeoplethinkthatsleeplossresides. Soatthispointinthetalk,thisisanicetimetothink,well,doyouthinkonthewholeI'mgettingenoughsleep?Soaquickshowofhands.Whofeelsthatthey'regettingenoughsleephere?Oh.Well,that'sprettyimpressive.Good.We'lltalkmoreaboutlater,aboutwhatareyourtips. Somostofus,ofcourse,askthequestion,"Well,howdoIknowwhetherI'mgettingenoughsleep?"Well,it'snotrocketscience.Ifyouneedanalarmclocktogetyououtofbedinthemorning,ifyouaretakingalongtimetogetup,ifyouneedlotsofstimulants,ifyou'regrumpy,ifyou'reirritable,ifyou'retoldbyyourworkcolleaguesthatyou'relookingtiredandirritable,chancesareyouaresleep-deprived.Listentothem.Listentoyourself.Whatdoyoudo?Well--andthisisslightlyoffensive--sleepfordummies:Makeyourbedroomahavenforsleep.Thefirstcriticalthingismakeitasdarkasyoupossiblycan,andalsomakeitslightlycool.Veryimportant.Actually,reduceyouramountoflightexposureatleasthalfanhourbeforeyougotobed.Lightincreaseslevelsofalertnessandwilldelaysleep.What'sthelastthingthatmostofusdobeforewegotobed?Westandinamassivelylitbathroomlookingintothemirrorcleaningourteeth.It'stheworstthingwecanpossiblydobeforewewenttosleep.Turnoffthosemobilephones.Turnoffthosecomputers.Turnoffallofthosethingsthatarealsogoingtoexcitethebrain.Trynottodrinkcaffeinetoolateintheday,ideallynotafterlunch.Now,we'vesetaboutreducinglightexposurebeforeyougotobed,butlightexposureinthemorningisverygoodatsettingthebiologicalclocktothelight-darkcycle.Soseekoutmorninglight.Basically,listentoyourself.Winddown.Dothosesortsofthingsthatyouknowaregoingtoeaseyouoffintothehoney-heavydewofslumber.Okay.That'ssomefacts.Whataboutsomemyths? Teenagersarelazy.No.Poorthings.Theyhaveabiologicalpredispositiontogotobedlateandgetuplate,sogivethemabreak. Weneedeighthoursofsleepanight.That'sanaverage.Somepeopleneedmore.Somepeopleneedless.Andwhatyouneedtodoislistentoyourbody.Doyouneedthatmuchordoyouneedmore?Simpleasthat. Oldpeopleneedlesssleep.Nottrue.Thesleepdemandsoftheageddonotgodown.Essentially,sleepfragmentsandbecomeslessrobust,butsleeprequirementsdonotgodown. Andthefourthmythis,earlytobed,earlytorisemakesamanhealthy,wealthyandwise.Wellthat'swrongatsomanydifferentlevels.(Laughter)Thereisno,noevidencethatgettingupearlyandgoingtobedearlygivesyoumorewealthatall.There'snodifferenceinsocioeconomicstatus.Inmyexperience,theonlydifferencebetweenmorningpeopleandeveningpeopleisthatthosepeoplethatgetupinthemorningearlyarejusthorriblysmug. (Laughter)(Applause) Soforthelastpart,thelastfewminutes,whatIwanttodoischangegearsandtalkaboutsomereallynew,breakingareasofneuroscience,whichistheassociationbetweenmentalhealth,mentalillnessandsleepdisruption.We'veknownfor130yearsthatinseverementalillness,thereisalways,alwayssleepdisruption,butit'sbeenlargelyignored.Inthe1970s,whenpeoplestartedtothinkaboutthisagain,theysaid,"Yes,well,ofcourseyouhavesleepdisruptioninschizophreniabecausethey'reonanti-psychotics.It'stheanti-psychoticscausingthesleepproblems,"ignoringthefactthatforahundredyearspreviously,sleepdisruptionhadbeenreportedbeforeanti- Sowhat'sgoingon?Lotsofgroups,severalgroupsarestudyingconditionslikedepression,schizophreniaandbipolar,andwhat'sgoingonintermsofsleepdisruption.Wehaveabigstudywhichwepublishedlastyearonschizophrenia,andthedatawerequiteextraordinary.Inthoseindividualswithschizophrenia,muchofthetime,theywereawakeduringthenightphaseandthentheywereasleepduringtheday.Othergroupsshowedno24-hourpatternswhatsoever.Theirsleepwasabsolutelysmashed.Andsomehadnoabilitytoregulatetheirsleepbythelight-darkcycle.Theyweregettinguplaterandlaterandlaterandlatereachnight.Itwas Sowhat'sgoingon?Andthereallyexcitingnewsisthatmentalillnessandsleeparenotsimplyassociatedbuttheyarephysicallylinkedwithinthebrain.Theneuralnetworksthatpredisposeyoutonormalsleep,giveyounormalsleep,andthosethatgiveyounormalmentalhealthareoverlapping.Andwhat'stheevidenceforthat?Well,genesthathavebeenshowntobeveryimportantinthegenerationofnormalsleep,whenmutated,whenchanged,alsopredisposeindividualstomentalhealthproblems.Andlastyear,wepublishedastudywhichshowedthatagenethat'sbeenlinkedtoschizophrenia,which,whenmutated,alsosmashesthesleep.Sowehaveevidenceofagenuinemechanisticoverlapbetweenthesetwoimportantsystems.Otherworkflowedfromthesestudies.Thefirstwasthatsleepdisruptionactuallyprecedescertaintypesofmentalillness,andwe'veshownthatinthoseyoungindividualswhoareathighriskofdevelopingbipolardisorder,theyalreadyhaveasleepabnormalitypriortoanyclinicaldiagnosisofbipolar.Theotherbitofdatawa