Fluctuating level of consciousness is seen in
Hysteria
Delirium
Dementia
Mania
Delirium is characterized by an acute decline in both the level of consciousness and cognition with paicular impairment in attention. Reference: Kaplan & Sadock's Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry, 11th Edition, page 697.
Symptoms and signs in psychiatry and classification