Ithaslongbeenknownthattotalsleepdeprivationis100percentfataltorats,yet,uponexaminationofthedeadbodies,theanimalslookcompletelynormal.Aresearchernowhascastlightonthemysteryofwhytheanimaldie.Theratsdevelopbacterialinfectionsoftheblood,_____theirimmunesystems---theself-protectingmechanismagainstdiseases---hadcrashed.
