I have had to have therapy and medication (Klonopin) to deal with panic attacks, so that's what I recommend. I would say sleeping is preferable to self-harm, but a good therapist can help you out with self-harm issues so that you will develop even healthier coping mechanisms. If I am not mistaken, sleeping as a means to avoid things is a sign of depression....or it is at least a form of avoidance, which is in itself, a symptom of PTSD. I wish you success in dealing with those pesky attacks!!!
LH