Six female rape victims with posttraumatic stress disorder (PTSD) were assessed for sleep disturbances. Five responded to cognitive -behavioral therapy (CBT) and one did not complete treatment. Sympatho-vagal balance was measured using heart rate variability (HRV) during rapid eye movement (REM) sleep. The treatment responders significantly decreased on HRV while the noncompleter increased. The responders also significantly decreased on sleep disturbances. The noncompleter remained unchanged. Thus a remission in PTSD symptoms following CBT accompanied a reduction in the HRV indicator of sympathetic predominance in REM sleep.