when i used to get them, they would last all day, they could be reallt intense and horrid, sometimes i could go a month without having them, but what brought them back was always me thinking oh ive not had them for ages, and sure enough they would be back. I think its the more you think of them the worse they are. Now if i get say one, i just say out loud, " do your worst because im not frightened anymore " then i would get i few thuds, then i would realise they had gone. proves to me how much my thinking played the biggest part in them