> I read once that a feeling of being watched was common with sleep paralysis.

I've only experienced a couple of times, but that was the most noticeable thing about it. I knew about sleep paralysis before I first experienced, so it didn't really concern me (as soon as I realised I was awake but unable to move, I knew what it was and roughly what to expect), but glancing over to my doorway and seeing a vague silhouette just standing there watching me is somewhat disconcerting nonetheless.