题目内容：
根据以下材料，回答题 MoreThan8Hours,Sleep,TooMuchofaGoodThing
1．Althoughthedangersoftoolittlesleeparewidelyknown,newresearchsuggeststhatpeoplewhosleeptoomuchmayalsosuffertheconsequences.
2．InvestigatorsattheUniversityofCaliforniainSanDiegofoundthatpeoplewhoclockup9or10hourseachweeknightappeartohavemoretroublefallingandstayingasleep,aswellasanumberofothersleepproblems,thanpeoplewhosleep8hoursanight．Peoplewhosleptonly7hourseachnightalsosaidtheyhadmoretroublefallingasleepandfeelingrefreshedafteranight'ssleepthan8-hoursleepers.
3．Thesefindings,whichDLDanielKripkereportedinthejournalPsychosomaticMedicine,demonstratethatpeoplewhowanttogetagoodnight'srestmaynotneedtosetasidemorethan8hoursanight．Headdedthat"itmightbeagoodidea"forpeoplewhosleepmorethan8hourseachnighttoconsiderreducingtheamountoftimetheyspendinbed,butcautionedthatmoreresearchisneededtoconfirmthis.
4．Previousstudieshaveshownthepotentialdangersofchronicshortagesofsleep--forinstance,onereportdemonstratedthatpeoplewhohabituallysleeplessthan7hourseachnighthaveahigherriskofdyingwithinafizedperiodthanpeoplewhosleepmore.
5．Forthecurrentreport,Kripkereviewedtheresponsesof1,004adultstosleepquestionnaires,inwhichparticipantsindicatedhowmuchtheysleptduringtheweekandwhethertheyexperiencedanysleepproblems．Sleepproblemsincludedwakinginthemiddleofthenight,arisingearlyinthemorningandbeingunabletofallbacktosleep,andhavingfatigueinterferewithday-to-dayfunctioning.
6．Kripkefoundthatpeoplewhosleptbetween9and10hourseachnightweremorelikelytoreportexperiencingeachsleepproblemthanpeoplewhoslept8hours．Inaninterview,Kripkenotedthatlongsleepersmaystruggletogetrestatnightsimplybecausetheyspendtoomuchtimeinbed．Asevidence,headdedthatonewaytohelpinsomniaistospendlesstimeinbed.
"Itstandstoreasonthatifapersonspendstoolongatimeinbed,thenthey'llspendahigherpercentageoftimeawake,"hesaid.
Paragraph2__________. A．Kripke'sresearchtool
B．Dangersofhabitualshortagesofsleep
C．CriticismonKripke'sreport
D．Awayofovercominginsomnia
E．Sleepproblemsoflongandshortsleepers
F．Classificationofsleepproblems
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