How many times in one nite?

I was just wondering, how many times can a guy, get it up and have intercourse with a woman in one night? I just don't know, but I seem to get going more than one time. After a rest for about an hour. I can go again, just like the first time. In fact, I some go three times in the same night. Please tell me if this is normal! I am not complaining, but I do get a little sore. And so does she!