睡眠(Sleep)

sleetispartofapersonsdailyactivitycycle.thereareseveraldifferentstagesofsleep,andtheytoooccurincycles.ifyouareanaveragesleeper,yoursleepcycleisasfollows.

whenyoufistdriftoffintoslumber,youreyeswillrollaboutabit,youtemperaturewilldropslightly,yourmuscleswillrelax,andyourbreathingwellslowandbecomequiteregular.yourbrainwavesslowandbecomequiteregular.yourbrainwavesslowdownabittoo,withthealpharhythmofratherfastwaves1sleep.

forthenexthalfhourorso,asyourelaxmoreandmore,youwilldriftdownthroughstage2andstage3sleep.theloweryourstageofsleep.sloweryourbrainwaveswillbe.thenabout40to69minutesafteryouloseconsciousnessyouwillhavereachedthedeepestsleepofall.yourbrainwillshowthelargeslowwavesthatareknownasthedeltarhythm.thisisstage4sleep.

youdonotremainatthisdeepfourthstageallnightlong,butinsteadabout80minutesafteryoufallintoslumber,yourbrainactivitylevelwillincreaseagainslightly.thedeltarhythmwilldisappear,tobereplacedbytheactivitypatternofbrainwaves.

youreyeswillbegintodartaroundunderyourclosedeyelidsasifyouwerelookingatsomethingoccurringinfrontofyou.thisperiodofrapideyemovementlastsforsome8to15minutesandiscalledremsleep.itisduringremsleepperiod,yourbodywillsoonrelaxagain,yourbreathingwillslipgentlybackfromstage1tostage4sleep----onlytoriseonceagaintothesurfaceofnearconsciousnesssome80minuteslater.