Are the discription of these seizures described in the Sira or Hadiths. I've seen this used quite a bit but can't seem to find the original source.
Yes they are. The surprising thing about the hadith themselves is just how much doubt the cast on 'accepted' doctrine.
But I won't rant here
http://www.searchtruth.com/book_display.php?book=59&translator=1&start=0&number=462#462Bukhari (Book #59, Hadith #462)
"..but I hoped that Allah's Apostle might have a dream in which Allah would prove my innocence. But, by Allah, before Allah's Apostle left his seat and before any of the household left, the Divine inspiration came to Allah's Apostle. So there overtook him the same hard condition which used to overtake him, (when he used to be inspired Divinely). The sweat was dropping from his body like pearls though it was a wintry day and that was because of the weighty statement which was being revealed to him. When that state of Allah's Apostle was over, he got up smiling,..."
Looks like he collapses, has a dream in which revelation occurs, while sweating... and then gets up.