Anytime I've experienced sleep paralysis. I don't have a specific story, but this sh*t freaked me out as a kid and still does.
It's a horrible feeling being conscious and knowing you're awake like you're being invaded by an entity, but you can't move or speak until it goes away.
I would rather have a nightmare because atleast I know it's not real. When I first started experiencing sleep paralysis I had no idea if it was real or if I was going crazy.
Holy hell, yes. I used to have experiences like that frequently a year ago or so and from what I could tell they had to do with sleeping problems (insomnia to be specific). Initially I didn't even realize what they were exactly. They seemed like nightmares to me and perhaps some of them were because I used to have dreams like that where I would "wake up" and see my room but something would be f*cked about everything in it. The spookiest variant of that is when you dream that you are looking at yourself in front of a mirror. I'm getting goosebumps just thinking about it. It's the freakiest sh*t ever because I was looking at a weird f*cked up version of myself (and usually the image keeps warping; the brain can't really maintain a consistent representation of reality in dreams).
The ones that were likely sleep paralysis all took place in my room. The typical sensation was that of lying in bed and feeling unable to move or get up. I think one of the first experiences of this sort involved my room being invaded by wasps (I hate them) and I couldn't get up to get away from them. Then the later ones got even more f*cked up. There was one where the windows opened or something. It started with a noise and I was looking at the windows in my room and then they burst open from the wind or something (but it sounded more like static). A similar one involved a silhouette of some sort that was visible outside my window which turned out to be an alien statue looking kinda figure but it looked like a mix of predator and sort of ancient soldier appearance. And lastly there was another alien sleep paralysis experience where a space ship was hovering in my yard (I could see it through the windows, but it was mostly lights) and I think another alien figure showed up outside and they were pulling me towards the ship from my bed while I was paralyzed but I decided I was having none of that and told them to f*ck off and I woke up. Sometimes even waking up is fake because you simply restart in the paralyzed state and it takes some violent attempt to shake your body or scream to actually snap out of it and wake up. It's f*cked up.
The last alien paralysis experience is likely an explanation of why a lot of people report being kidnapped by them. For me it was a believable experience to some extent but I think I was also somewhat aware that it couldn't really be true while experiencing it. It's sort of a state between normal dreaming and lucid dreaming. Sometimes during lucid dreams, which used to be frequent for me, I would eventually forget that I was dreaming even though I initially knew it. Sleep paralysis can be like that.
I began walking again, but before I could take a handful of steps, a shadowed figure the size and shape of a human shot across the path from one cluster of headstones to another, no more than thirty feet ahead of me, and vanished. Remember, I could see clearly, and the headstones were not so tall that you couldn't easily pick out some person or animal running through them. But the figure was just gone. No chances taken! I turned and ran back to the street from whence I came like a scared kitten.
If I experienced something weird like that I would probably either start screaming "hey, who are you" or just start running towards whoever was there. I get scared too in situations like that but I would much rather confront it directly than just run away. Having said that, I think the brain is made in such a way to deceive you when the eyes can't really perceive what is happening. In other words, brains like to fill in the gaps and the evolutionary reasons for this are kinda obvious. In caveman days (or even earlier than that), a brain that would perceive threats based on very little evidence (i.e. an inability to distinguish an entity in the dark) would have been more prone to facilitate survival. The ones who ignored a shadow or figure in the dark that was an actual predator or something likely died off. If you were somewhat scared before you entered the cemetery it's possible that you became more paranoid and thus your brain started to fill in the gaps, whatever it was that you couldn't see. Here's how you can experience your brain filling in the gaps more or less directly.
I have a watch in my room that once ran out of batteries and it stopped. It has the usual hour, minute, and second arms. I used to sit a certain distance from it and I have the habit of checking it when I'm at the computer so an image of the clock was sort of burned in my mind over the years. The funny thing about that image is that it is actually a moving image. When the clock stopped and I looked at it as I usually look I noticed that for a few seconds I could see a faint but somewhat visible moving arm on the clock (the one that measures the seconds) but when I looked more carefully there was no movement at all since the batteries ran out. My brain simply filled in the information that the arm was moving even though the real arm stopped because I wasn't really paying close attention (or rather I could not see the details in full at first). It is the same thing with shadows in the dark. The brain has a tendency to interpret them badly based on little information (i.e. reduced visibility). I can tell you that being scared or paranoid makes it worse.
Early this year I got pneumonia and had a nasty fever. One night I noticed that for whatever reason I started to think a lot faster. It was like I was on drugs. Initially the experience was nice. I was moving from one topic to another very fast in my mind and I kinda felt like a genius of some sort lol but the downside of this experience was intense paranoia. For some reason, as I was about to shut off the lights and go to sleep the idea that there might be something outside, an alien or something like that, entered my mind and I was unable to leave it alone. I think I even got out at one point and I had to make a real effort (rationally) to remove that paranoia from my mind but while I was experiencing it it really felt like there was something outside, in the dark, wanting to get me. Moral of the story: paranoia is bad and high fevers can make you feel like you're high as f*ck.
I realize that this is a huge post but I have a few other weird experience I would like to share. One goes back to my childhood and involves something that I witnessed with my sister (I have to ask her at some point if she still remembers it). We were out in the yard at night and noticed something weird in the sky. There was an object in the sky, a white ball of some sort, that was moving slowly in the distance. It was probably a few hundred meters to a kilometer away and it looked like a white oval shape slowly drifting away. I don't remember much of the details but we told our parents and you can pretty much guess what the response was (disbelief). At the time I thought it was something to do with aliens but I later realized that there is one rare phenomenon that likely explained it which is ball lighting. There are clips of this thing on YouTube and it sort of looks like what I saw but not really. The thing that I saw was probably much bigger than those videos show but I think it had to have been that and it's really rare and no one knows exactly what causes them to appear.
The other weird experience that was more recent happened last year and this year. If you look up the term "the hum" you'll find videos or reports of people hearing a noise at night or during the day of no apparent origin. Some of these reports were investigated with no luck as to identifying the source of the "hum". The hum that I heard here sounded like a tractor engine in the distance or something like that but it made no sense to me. For starters, there were several days in a row when I would hear this at 2-3 A.M. when no sane person would chose to operate any sort of farming machinery or whatever. There are indeed fields nearby but who would work on them that late at night? This year I heard it again and now I'm thinking it might be a train or something since there's a train station nearby. It's plausible but why is there a train remaining stationary days in a row with its engine turned on then? I went out several times and tried to get closer to the noise but I would have had to leave the yard and go into the garden (the train lines essentially go through my garden) and then go even further than that. I guess if I had a friend to come with me and investigate would have made it less weird than one guy walking around at 2-3 AM alone. Whatever it was it's gone now.