Have you ever fainted?

[Signalstar]

I just fainted during my karate lesson and it made me really sad :( I feel  so humiliated. I just became dizzy after a round of exercises and collapsed to the floor. I never lost consciousness at all. Anyway I stopped class immediately and have to schedule a doctor's appointment to make sure everything's okay. 

I think my problem is lack of sleep but I can't help it when class/work keep me so busy.

Anyone have any fainting stories they'd like to share. It would cheer me up knowing I'm not the only one.