Obstructive sleep apnea and depression

Is there an association between obstructive sleep apnea (OSA) and depression? OSA is a common breathing-related sleep disorder. There have been reports that depressive symptoms can be associated with this sleep disorder. A number of investigations have addressed this issue. Although some have found no correlation, most studies have concluded that there is an association between OSA and depressive symptoms. Other investigations have shown that depressive symptoms improve with treatment of OSA, and that untreated OSA may contribute to treatment resistance in some cases of mood disorders. Within the framework of current psychiatric diagnostic criteria, the depressive symptoms associated with OSA can be viewed as a combination of a mood disorder secondary to a primary medical condition and an adjustment disorder with depressed mood. The question of whether OSA causes depressive symptoms can perhaps be best answered by viewing OSA and depression as having certain symptoms that are common to both disorders.