I get exactly the same thing: perception of huge numbers, and the infernal need to perform some calculation. For me this is often combined with getting out of bed and walking about in delerium. It's very frightening. I once tried to 'get out' of the nightmare by trying to walk through a wall, which wasn't very successful, and just made me more confused. I'm glad to hear I'm not alone. Has anyone else experienced walking at night too?

Thanks