ICU delerium is a real thing. It's got something to do with background noises, barely overheard conversation, sensory deprivation, anxiety, and discomfort.

My mother went through that and was fine after a few days out of ICU. She was convinced they were trying to poison her. It was frightening!

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2154033/#:~:text=Abstract,are%20often%20preventable%20or%20correctable.