I'm still a little sore from krav maga last Sunday. I don't think it's just the strain, although I'll stretch more and get used to the pain of attacking or defending. I had a hard time sleeping last night, too. A series of nightmares...
After learning a tiny fraction about defense against a knife, of course my mind goes and constructs a knife attacker to see how that might work. In my dream, I felt the fight-or-flight response (and definitely leaned toward flight!). The strange thing was that it didn't stop there... Rather, I ended up flashing back to the last time I felt a really strong fight-or-flight response, which had nothing to do with knives and everything to do with overhearing my name in conversation. That really sucked; I just couldn't stop my heart from racing.
And then I ended up dreaming someone I know was really really sad, and I just couldn't figure out how to explain things to cheer her up, and I just felt terrible.
So yeah, not quite restful sleep for me yesterday. Strange, isn't it? A knife grabs attention, but it's worse to wake up and realizing that your phantasms are less obvious and more real.