The only time I hallucinated was after a single-day double crossing of the Grand Canyon, a 15-hour run/hike iirc. I would see a random tetris game in front of me even though I never played.
Sleep deprivation in my experience can produce similar effects.
It feels like a wakeful dream. Where despite having open eyes and even interacting with the world on some level, the brain is off watching an entirely different movie.
I had a similar experience on a big multi-peak one day traverse. It was unusually hot/humid and turned into an 18 hour sufferfest. Thankfully I wasn’t the one driving afterwards, as I was hallucinating shadowy people standing in every open space along the side of the road.
Interestingly, I’ve done a few similar hikes and had plenty of energy after to cook a big pot of chili at our basecamp and enjoy a couple of beers. Exhaustion is weird.
It was definitely vivid. I can't say that I was convinced it was there because tetris blocks do not appear in nature, so I obv knew it was a hallucination.
It feels like a wakeful dream. Where despite having open eyes and even interacting with the world on some level, the brain is off watching an entirely different movie.