I've had panic attacks for no real reason, too. I think of them like seizures. There may be things that trigger them, but sometimes, they just happen. And I think of them as seizures not just for that reason, but because they just sort of take over your body. Yes, sometimes you can prevent them and calm yourself down, but I tried to come up with something to try to explain them to people who don't understand, and seizures, being physical attacks generally, are more accepted in society than panic attacks. Seizures have some similarities, and that's what I've used. Still doesn't seem to make people understand or accept, though. *Sigh!*