What is delirium nocturnum?

Not common term. Literally, confusion at night. Many illnesses have increased symptoms at night includg dementia where the term sundowning is used.
Going nuts at night. Delirium is a term used for abrupt onset of a confused, disoriented, psychotic (out of touch with reality) state. It is usually short lived, but depending on what kind of delirium, it could be very serious, even fatal (such as delirium tremens caused by abrupt untreated alcohol withdrawal). D. Nocturum is also called sun downing, where certain people develop delirium around sundown. Needs doc.
Not sure. Confusion & delirium at night could be sundowning or exercebation of behaviour & psych symptoms at night ?