My daughter had them & yes they were called night terrors, usually occuring around 18 months. I was told by Dr that it is when they start to remember things they have seen during the day & start to understand fear etc...
I was told to let her cry 5 mins go in reassure her, then walk out & if she started screaming again to go back in after 10 mins etc... I tried this for 2 nights, it was breaking my heart & I desperately needed sleep!
It was awful as Maddy was literally standing up shaking in her cot trying to get out, I ended up leaving a lamp on in her room & giving her a book & after about 2 nights of crying abit, she went back to sleeping through the night...
Thosae 4 nights of broken sleep are the things I am not looking forward to in having another baby!
I am a real sleep needing person, eeven if it's only 5 hours, but broken sleep it just wrecks me!