Fred, Barney, George, and Bart are ten years old, and each suffers from a different sleep disorder. Fred occasionally shifts suddenly during the day from a normal waking state into several minutes of sleep, during which time he has very little muscle tone and is effectively immobile. Barney walks in his sleep (but does nothing else), while George sometimes moves to act out his dreams. Bart has nightmares (not sleep terror disorder). Who is least likely to be in the REM stage of sleep when he exhibits his symptoms?