The only thing that works for us is to put DS in our bed and talk to each other. It has a calming effect but doesn't work entirely. He is totally unresponsive to us and just keeps crying out 'mummy' even though I am lying there with him. So draining so I know how you feel. I do try to rouse him. I know if I can get him to drink some water the episode is almost finished although it usually takes 20mins or so to get to that point. DS is growing out of it though and hopefully yours will too. He used to do it every third night and now (about a year on) it is about once a month. Big hugs.