The geometric nightmares! I had those as a kid whenever I was very tired or had a fever, and kept having them until my late teens. Never seen them described and didn't know it was a thing.

Same here. I also recall them when I had fevers in my childhood.

I attribute them to the fact that, while trying to sleep with a fever, my eyes are half-open, and any sharp object becomes a visible geometric shape that my brain attempts to comprehend but almost fails to. I still experience them in adulthood. I’ve never had sleep paralysis, but whenever I think of people who have it, I imagine it feels as debilitating as these half-sleep experiences where you’re unable to move while your brain processes distressing memories.

“Geometric Nightmares” is not a scientific name. It is simply the name given to this phenomenon in forums [1][2] where people discuss and share their experiences.

[1] https://www.reddit.com/r/Dreams/comments/7ofu86/x/

[2] https://www.reddit.com/r/geometricnightmares/

Last time I stopped smoking cannabis I got these for a couple days. They are intense. The most recent was kind of like taking a slow rollercoaster ride through three black hole sized perfect spheres orbiting nothing. Another one was less geometric but was basically me getting sucked into a black hole. Both had this almost lucid dreaming feel where my entire sense of self became condensed into a single point... but I was still there, aware of what was happening... it was incredibly memorable.

Interesting. I recently discovered that my sister and I have identical geometric nightmares, down to every detail, while everyone else I mention this to thinks it's insane. I wonder whether there's a genetic aspect?

I had a recurring abstract nightmare as a small kid (don't think it was related to fever but I guess those were pretty common) which was basically about a line, gradually becoming messier and messier until it was all just a big jumble. I could never explain it to anyone else, but it terrified me for a time.

I also had something like this. Again as a kid, with fever. Very unsettling. But I don't remember having it as an adult. Strange.

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