Delirium is a state of mental confusion or a syndrome characterised by fluctuating or decreasing cognitive impairment along with behavioural abnormalities. It may includes the following features: Global cognitive deficit, Varying conscious level, Memory impairment, Strange behaviour, Disordered thinking, Disturbed perception, Mood swings Delirium can be divided into 3 basic types: HYPERACTIVE DELIRIUM Easily diagnosed in which the person becomes overactive. Psychomotor changes includes restlessness, agitation, increased arousal, inappropriate behaviour, delusions and hallucinations. HYPOACTIVE DELIRIUM Person becomes underactive. Psychomotor changes includes lethargy, sedation, retardation, excess somnolence. Often gets mistaken for depression or dementia. MIXED DELIRIUM Combination of both the hyperactive and hypoactive type with variable presentation of symptoms.