Hi there.  I experience these, too, off and on, but it happens when I've been asleep for about an hour.  I've read this is called hypnagogic hallucinations.... it IS quite scarey because I really think someone is in my room. Another odd thing I do is think the rings on my fingers are missing and I actually get up and look in my jewelry box, though by that point, I realize it's the same old thing.  I do not know why this happens.  Since I've learned what this is, I don't have the 'person in the room' nearly as often. 

Oh, and I forgot to tell that I even wear a sleep mask at night to cover my eyes (since I wear Ortho-K lenses) and I don't need my eyes to potentially dry out.  The 'night terrors' as you called them were happening before the night mask and after.....  I wish it would stop.  Years ago, I used to dream my ex-husband was trying to kill me, but now I wonder if these was part of the same situation.  It IS annoying.