True about delirium are all except
Preserved attention
Disturbed sleep
Disorientation
Hallucination
Delirium is characterized by an acute decline in both the level of consciousness and cognition with paicular impairment in attention. A life threatening, yet potentially reversible disorder of the central nervous system (CNS), delirium often involves perceptual disturbances, abnormal psychomotor activity, and sleep cycle impairment. Reference: Kaplan & Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry, 11th Edition, page 697.
Symptoms and signs in psychiatry and classification