Hi Heather! YES! I have BTDT- First, I want to be sure it is most likely a Night Terror- typically this happens in the first 1/3 of the night's sleep so- between 8-12PM? Your LO definitely does not seem aware of you? Sounds like it...
If it's any comfort to you, your LO is NOT experiencing a nightmare per se. If it is a NT, most likely your LO has NO recollection of it, and is completely unaware of it the next day. Kids that have nightmares usually wake unhappy, really frightened and if it persists will become scared of their room/dark, etc.
Night terrors on the other hand seem to be more of a physical release of pent up energy from what I read. They do seem to run in families- I slept walked as a child, my DH still night talks at times.
Nick (my DS) went through this from about 8-10 months and it peaked at 9 mos- when he was really learning to walk steadily. He also had major sleep walking/crawling. We wound up hiring our sitter to sleep over in his room a few nights as I was up at 9-11 for NTs, then 2-5 for sleepwalking related wakings, ... ugh. Once Nick ran at 10 months, the NTs stopped.
It doesn't help him to wake him. I read that the most helpful thing to do was just to be there and put your hand on your child gently, and rub their back, saying "mama's here" or some soothing phrase until they stop. Their body is just moving, their mind is NOT actively dreaming. They are unaware of you, most likely. So do what you are comfortable with, standing by the edge of the crib.
You have my sympathy/empathy, ...it is sooooooo spooky/eerie sounding and looking. FWIW, our MD said that NTs can be a sign of a creative/sharp mind.
If you need more info, feel free to PM me, also check out Richard Ferber's book "Solve your child's sleep problems (2006 issue). I am not a fan of some of his methods, BUT his information on NTs, sleepwalking and major sleep disorders is the most comprehensive I've found. Your library probably has a copy. Most bookstores do.
HUGE hugs- BTW, how old is your LO now? Any major motor stuff happening?