I don't remember being knocked out, nor do I remember the day prior to it happening, or much of the day after. The day after is there, but hazy.
The first guy I knocked out was at a seminar on pressure point fighting. My partner (who I didn't know, but was my senior) told me I wasn't hitting him hard enough and he really wanted to feel the effect of the strike. I realized (as he was falling) that power had not been the issue, but rather accuracy.