Sleep and depression - theory and practice.

BACKGROUND Sleep disorders are particularly common in the primary care setting, and are intimately interlinked with depression. OBJECTIVE This article aims to review the relationship between sleep and depression, with an emphasis on the foundation and clinical salience of this relationship. DISCUSSION Depression is the most common cause of insomnia, and insomnia is highly prevalent in depression. This association has a well characterised physiological foundation. Sleep disorder in depression has prognostic and therapeutic implications. Residual insomnia after remission of depression is predictive of relapse, and prominent insomnia predicts a poorer treatment outcome in depression. Evidence based management involves integrating both pharmacological and behavioural strategies; the latter includes sleep hygiene and regulating diurnal rhythms.