H.
Hi J.. I'm not a doctor but I can tell you that I had two out of three children wake up doing this as well. I asked the doctor about my situation and he called it "night terrors". He said they are actually still asleep but are crying or screaming in their sleep. He said it is normal and not to be concerned about it. He said the best thing to do was to go in their room and rub their backs and comfort them while not waking them up. They will eventually stop and go back to sleep. My second child started this as early as 8 mos and scared us to death! Now my third child started it about the same time and still does occasionally and she is over 2 years old. My son hasn't done it since he was an infant and is now 3 years old. Hope this helps a little...
H.