Sleep research in depressive illness: Clinical implications —a tasting menu

It is well established that sleep patterns are altered in psychiatric disorders and represent a very common presenting complaint. Even though sleep disturbance is often a key feature of many psychiatric conditions, its most prominent role has been in mood disorders. The clinical implications of disordered sleep in mood disorders represent the focus for this paper. Specifically, the following questions will be discussed: (1) How sensitive and specific are the sleep findings in depressive disorders? (2) What are the characteristics of sleep in depression and subtypes of depression? (3)Are sleep changes in depression episodic (state-like) or persistent (trait-like)? As we point to specific characteristics of sleep in subtypes, it is important to note that more sophisticated analyses of sleep measures provide an opportunity to pinpoint changes between delusional/nondelusional depression or endogenous/nonendogenous depression. Furthermore, differences among subtypes will be best understood if we realize that both age and gender affect sleep measures in a consistent manner. Therefore, for example, there is a more robust separation between patients and controls in older individuals than in younger individuals.