I love movies... ...But I hate "Movie Knock-outs". You guys know what I'm talking about - right? A good guy, in a movie, needs to incapacitate someone like a guard. So the good guy sneaks up and hits the guard (or who ever) with an object of some kind (lamp, pipe, vase, branch, etc...) and the guard is "knocked out", but is otherwise fine. Oh my God that is SO ANNOYING!!!!!! Why do they keep using this unnecessary and STUPID cliche in movies!?! I'm not a doctor - but I'm willing to bet that if you hit someone hard enough to incapacitate them - then this is how it would happen:
22% - instant death
32% - unconsciousness, vomiting, bleeding, death occurs in less then an hour unless hospitalized.
27% - severe brain damage requiring hospitalization.
18% - spinal injury requiring hospitalization.
1% - unconsciousness with no permanent consequences.
And what gets me the most is how UNNESSESARY it is as a plot device! If a writer does not want to show the hero killing the guard - then have him use chloroform or a taser! Or have him over power the guard with a struggle. CHRIST! WHY why why do they keep using this stupid cliche!?!?!?!?

I knocked someone the fuck out, twice, though it was not the same person.
Once when I was playing soccer I bounced my cleated foot off of anothers head playing the ball. He was unconscious for about 10 minutes and except for a large lump on his temple and a black eye he was quite fine.

The next guy I was in a fight with, big huge skinhead asshole, I knocked him out for about 10 minutes as well with a well placed fist to his noggin(TAKE A NOTE---HITTING SOMEONES HEAD WITH YOUR FIST HURTS LIKE A BITCH). He recovered as well with a hell of a headache

So in truth you can knock people out BUT I would never recommend it. It can cause serious injury.

Besides it is fucking hollywood, as long as it looks good and gives the writer an easy out why the hell not. I always suspend my belief at the doors of any movie theater.

I have trouble doing that. Realism (or a lack of it) can make or brake a movie for me.