: when sally gave sam the ambien, everything changed. suddenly he could talk, though his speech is slurred. >> hello, sarah. >> reporter: hi, sam. it's great to hear you talk. >> it's good to be talking. >> reporter: he was no longer trapped in his body. turns out sam's mind was always working. he just couldn't let anyone know. i understand you're good at math. what's 20 times 30? >> 600. >> reporter: very little research has been done to understand why ambien wakes up certain brain injured patients but experts say the active ingredient zolpidem triggers blood flow to certain areas of the brain. yet it appears less than 10% of brain injured patients respond to ambien, and very few as dramatically as sam. no matter. sally nielsen who said she always knew sam was in there is just glad she tried it. sarah james, nbc news, brisbane, australia. >> you can see more of sarah's remarkable report tonight on rock center at 10:00/9:00 central here on nbc. when we come back here tonight after getting a late start he's taking orders from guys nearly