That was completely wild. This is also one of my favorite explanations for both historical and modern tales of haunted houses.
In the story of that historical incident, the 1921 “Mrs. H” account, they experienced many of what we think of as the really classic signs of a haunting. Aside from moving into a run down, semi-creepy house – that’s how these stories always start, right? – they experienced things like mysterious noises as if someone was violently rearranging the furniture in the middle of the night. They heard voices, felt as if they were being watched or followed, heard tapping in the walls. And it was as if there were ghosts acting on them physically: shaking the bed, holding them down, yanking away the sheets. “Mrs. H” sees ghostly figures sitting at the foot of her bed, and describes them in detail. And it all turns out to be a carbon monoxide leak: the furnace is fixed, and the haunting immediately comes to an end.
What’s scariest about carbon monoxide IMO, and what’s really illustrated by that reddit story, is how quickly and thoroughly carbon monoxide poisoning can just disconnect you from reality. You think you’re taking appropriate action and thinking clearly and remaining essentially yourself, while half of what you’re doing, pretty much all of what you’re experiencing, turns out to be sheer hallucination. It has to seem so real on every level, but none of it is. It’s scary to think how easily our entire perception of the world can just be wrong, and we have absolutely no concept of it.
(My other favorite explanation for hauntings is infrasound. I don’t necessarily disbelieve the idea of some sort of life after death or things like that, I try to maintain an open mind because our understanding of our universe is seriously not as thorough as we’d like to think, but the scientific possibilities for what could cause the symptoms and sensations of a haunting are completely fascinating. Like who would’ve figured you could get such vivid, convincing, visceral effects from something as obscure as sound outside your ability to actively hear, or gas you can’t detect.)
