A substantial historic and growing preclinical literature documents autonomic nervous system (ANS) dysregulation in patients with PTSD. Preliminary results suggest that portable heart rate variability (HRV)/ respiratory sinus arrhythmia (RSA) biofeedback appears to be a promising adjunct treatment for disorders of autonomic arousal. The StressEraser, a HRV/RSA biofeedback device, is indicated for relaxation, relaxation training, and stress reduction. The StressEraser is a small handheld device that measures and displays real-time RSA, a measure of HRV, via an infrared finger sensor.