Recovering from a severe chest infection, a 79-year-old man becomes convinced that small rodents are scurrying across his hospital bedsheets at night, reacting with genuine terror and swatting at them repeatedly. During the day he is calmer, though still unable to say what day it is, and he recognises his wife immediately whenever she visits. What is this presentation?

This is a dream-like change of consciousness: disorientation for time and place with preserved recognition of person, vivid and frightening visual hallucinations (classically small animals), and a fluctuating course worse at night. It is not lowering of consciousness, which is specifically characterised by the absence of hallucinations, illusions, and restlessness — the opposite of what's described here. It is not a primary psychotic hallucination, which would typically occur with clear consciousness rather than alongside this degree of disorientation. And it's more than ordinary sleep-related confusion, given the vivid, terrifying hallucinations and disorientation for time and place.