sanscript: Not exactly a normal "ghost" story, but here it goes...
I never have any nightmares ever since junior high (7-8 grade?) because I somehow learned to recognize when I was dreaming and take advantage of it. Doesn't fully work every time, but the thing is that I crawl up in fetus position if I feel too threatened and it feels like I'm being scooped up, and then I wake up. These kind of dreams are since more like uncomfortable dreams.
Couple of years ago I experienced my worst "episode" ever. As I lay beside my wife and had just said good night, I'm looking out of the window trying to think of dull and mundane things, like dancing eskimoes or hopping grasshoppers through some tall grass.
After a few minutes everything turned completely weird, and I got scared for the first time in a long, long time. I mean, really scared. Some dark twisted filter was added to my sight, and I did notice that sometimes the light spectrum was ever so slightly shifted. Warped maybe, in and out. I realised I was actually fully awake because this didn't feel like a dream. Felt all too real for that. Awake but unable to move, completely paralysed while I watched. No matter what I tried I just couldn't move for awhile. I tried to scream...
And then suddenly I heard a sound which sounded like an electric industrial transformer (like those one use to step huge voltages up and down), only more loudly. And then completely blank, and then back again in an instant.
I was relatively calm as if nothing had happened when I got control over my bodily faculties again. In other words, my heart wasn't trying to get out of my chest, which was kinda odd in itself due to the recent experience. In any case, I immediately woke my wife up and told her about it, and asked her, however, she had neither seen nor heard anything.
As I try to recall I get the distinct feeling something did happen, though I can't put my finger on it, and I'm pretty sure I actually was awake.
T o this day I still ask myself; what
really happened?
Sleep paralysis.
Your body enters sleep state (hence the inability to move) but your brain remains semi-conscious and applies dream-like, but crazy realistic hallucinations to its perception of your surroundings. And because it is aware of the muscle paralysis, the hallucinations are often nightmares of suffocation/restraint, evil presences, etc.
I've had my blanket come alive and try to strangle me during one episode. Another time I was trapped in a cycle of (seemingly) waking up, getting up and starting my morning routine only to wake up in bed again, get up, wake up in bed again, lather, rinse, repeat. Sometimes it's just ridiculously loud buzzing noises right next to my ears. It can get pretty freaking scary but it's ultimately harmless.
Edit: It's also what AnimalMother117 described.