Troubledbyboutsofsleepwalkinganddisturbingnightmares,graduatestudentSarahFostergoestoheruniversitysleepresearchcenterforhelp.Butwhenshewakesupafterherfirstnightofbeingmonitored,theworldshelivesinseemstohavechangedinsubtle,Twilight-Zone-esqueways.