Kleine-Levin Syndrome (KLS) is characterized by periodic, sudden onset episodes of hypersomnia ,compulsive hyperphagia and behavioral-emotional disorders (like uncontrolled hypersexuality, irritability, impulsive behaviors). Episodes last from 1-2 days to 1-2 weeks and between the episodes remission is nearly complete. Depression, confusion, and thought disorders are often associated with symptomatology and may cause other psychiatric disorders (like schizophrenia, mood disorders, conversion disorder) or substance abuse to be considered in diagnosis. Even if this complex symptomatology cannot be easily explained by a single mechanism, a diencephalic—hypothalamic dysfunction is suspected.

The objective of this article is to review the literature on Kleine- Levine Syndrome, a rare disorder and to point out the problems in differential diagnosis by a case report. KLS is psychiatrically evaluated and psychiatric correlates of KLS including relationship with affective disorders and the possible emotional effects of episodes are discussed.