L.S.
Night mares and night terrors are not something that can become habit, they either are or they aren't. And you can't control them.My son is 8.5 and still has both. He does have them routinely, though. But I never let him suffer needlessly. I always go to his bed and try to comfort him. Sometimes he doesn't even know I am there, like he is stuck in his dream. Even with the lights on, his eyes open and me talking to him etc. Sometimes it was a bad dream and he will awaken crying, but knows where he is and is comforted. Either way, they are real to him. He has had them since a young age. We have tried everything. Nightlights, plain food before bedtime, no scary movies, etc. If you ever researched it and there were suggestions then we did it. In an effort to try to relieve his distress, not necessarily mine. They have gotten better and he does seem to be outgrowing the frequency of them as he gets older. I would think that the nightmare is one where she can be comforted and knows where she is. A night terror is one where she may not necessarily be asleep, but she isn't "with" you either and doesn't seem to be able to be comforted..it is kinda like sleep walking (I have two of those also),but sleep screaming and crying...even with the eyes open. At 22months she is at the prime age for bad dreams to start, for whatever reasons. She is more aware of her independence, new steps in her life, feelings of anxiety she can't express or know what it is enought to understand. Whatever the reason, they are real to her.
My best advice is to comfort her and teach her that she is safe and how to comfort herself. If that doesn't work then maybe a pallet on the floor next to your bed would help. Have done that for many a year and is still in use with above mentioned 8yr old. My 12 yr old still sleepwalks alot also. But doesn't seem to have the night terrors, like my younger.
Sorry can't tell you more or be more helpful. It's just part of their growingup!
Good luck,
L.