This happened 3 or 4 years ago.
At that point in my life, I was going through a real "horror" binge. I was watching all kinds of horror movies, playing frightening games (Silent Hill series in particular) and I would enjoy going out to eerie locations, and doing everything I could to really bring on the sensation of being creeped out. (I still do love the feeling, but don't go out of my way to find ways to get it)
At this same time, I was going through my first real spiritual phase, trying to learn how to meditate, go out of body, etc. Anyways, there was a week long period at one point in there, where I found that in bed at night, if I concentrated hard enough, focusing my mind on spirits and evil things and such, that I could sort of shift my consciousness, or at least my awareness, to the point where I was still awake, fully aware of my surroundings, and yet things were quite off.
Each time I did it, there were a few things that remained constant - The geometry of my room seemed askew, odd angles and such, enough that it was recognizable as my room, yet completely unfamiliar- and the shadows were in higher contrast, and seemed to pulse and grow across my room, almost as if they were liquid against the walls.
The first time, it was dark, and there was mostly just the odd moving shadows for a bit. Then something that sounded like that crinkly plastic "hay" they put in Easter basket rustled above my head on the headboard. Didn't think a whole lot of it until it fell off the headboard and landed on my face. Felt like the plastic hay too.
Quickly grabbed the mass and tossed it over the side of my bed, and lay there staring at the liquid darkness for a few seconds, before I heard it rustle, and felt the stuff collide with my face again. Tossed it off the bed, wrapped the pillow around my face, and counted to 5, bringing myself out of that state.
Pulled away the pillow, opened my eyes, turned on the light, and looked over the edge of the bed at nothing different than it had been when I went to bed.
The next few times looked and felt similar. Although there were dark shapes looming over the side of my bed, and standing in contrast against the light coming in my window. I stayed there, studying and watching them as they seemed to sway slightly with the shadows. Each time, once I had enough, the pillow and count brought me out. The 4th time I could feel the bed being stepped upon by what seemed some kind of heavy quadruped animal. I could hear it breathing, and its face got closer and closer until the point I could feel it sniffing my own face. Up goes the pillow and the weight fades away. The 5th and final time I tried it. I saw a distinct humanoid shape with a wide-rimmed hat at the foot of my bed. I was fine with that until I started feeling it climbing onto the bed overtop of me. I left and decided not to try it again.
I want to point out that at no point during any of these "excursions" did I feel threatened by the things I was seeing and feeling, only curiosity. They seemed to wonder how I could sense them.
To this day I don't know if I was actually forcing my consciousness into another "plane" so to speak. If I was, whether they were actual inhabitants of a spiritual world that were surprised, I could suddenly notice them, or demons that were trying to make me comfortable with them. Or if not, just somehow able to bring myself into a day-dream like state where my imagination was superimposing itself over reality.
However, as the animal I was sensing was very similar in shape and size to the creature I believe to be my guardian spirit, I find it hard to believe that I wasn't tuning into someplace I wasn't expected.
Would love to hear any ideas or suggestions!