Perhaps not so much for why time seems to slow down in an emergency, but in that it seems to move faster the older we are.

http://news.yahoo.com/s/livescience/20071212/sc_livescience/whytimeseemstoslowdowninemergencies  

Eagleman added this illusion "is related to the phenomenon that time seems to speed up as you grow older. When you're a child, you lay down rich memories for all your experiences; when you're older, you've seen it all before and lay down fewer memories. Therefore, when a child looks back at the end of a summer, it seems to have lasted forever; adults think it zoomed by."