Solution:

Delirium, also known as acute confusional state, is an organically caused decline from a previously baseline level of mental function. It often varies in severity over a short period of time, and includes attentional deficits, and disorganization of behavior. It typically involves other cognitive deficits, changes in arousal (hyperactive, hypoactive, or mixed), perceptual deficits, altered sleep-wake cycle, and psychotic features such as hallucinations and delusions. Delirium itself is not a disease, but rather a set of symptoms.