It'sgettinglate.You'retryingtofinishabook.Butyoureyesstarttofeelvery1.Onlytwomorepagestogountil...zzzzzzzzzzzzz.
Sleepingispartofournaturaldailyrhythm.Oureyesclose,ourbodiesrelax.Wedonot2tolightornoise.Everythingaboutusseemstoslowdown.Everything,thatis,exceptourbrains.Howdoscientistsknowthis?Scientistsusespecialwiresandmachinestostudybrainactivityduringsleep.Theyattachaspecialmachinetosleepingpatients.Thismachine3brainwaves.
Scientistsfoundthatthereareseveralstagesofsleep.Duringonestageofsleep,calledREMsleep(rapideyemovementsleep),ourDramscanbeasactiveastheyarewhenweareawake.We4havethreetofiveperiods(片段)ofREMsleeppernight.Thisiswhenwehavemostofourdreams.
Surprisingly,scientistsdon'tknowexactly5wesleep.However,theyhavesomegoodideas.Manypeoplethinkthatsleepinggivesourbodya“time-out”soitcanrepairandbuilditself.Somechemicalsthatmakeyougrowarereleasedwhenyousleep.Otherchemicalsthathelpyoufightdiseasearealsomoreactivewhenyourest.
Sleepingmayalsobeimportantfor6.Somestudiesshowthatpeoplerememberthingsbetterafterthey"sleeponit."Inmostcases,youwakeupinthemorningfeelingrestedandrefreshed.Thatis,unlessyou'vehadaterribledream.7,yourheartmaystillbepounding(砰砰跳)fromanightmare(恶梦).
A
warm
B
heavy
C
narrow
D
dry
A
lookforward
B
payattention
C
doharm
D
giveresponse
A
records
B
attracts
C
causes
D
requires
A
hardly
B
nearly
C
usually
D
especially
A
how
B
why
C
where
D
when
A
driving
B
writing
C
learning
D
playing
A
Atmost
B
Atlast
C
Inaddition
D
Infa