Obstructive sleep apnoea and depression: diagnostic and treatment implications

Sleep apnoea (OSA), a common sleep disorder, is well recognised as a cause of morbidity including psychiatric disorders. There is increasing recognition of the link between OSA and depression. Sleep changes are intrinsic to depressive disorders, most notably disturbances of REM sleep; OSA causes predominantly REM sleep disturbances. The neuro-vegetative features of depression are similar or identical to the symptoms of OSA- an issue which has not achieved wide clinical recognition. A growing number of studies confirm the statistical link between the two conditions. The implications are twofold: OSA needs to be excluded in cases of chronic or resistant depression and treatment of OSA will make it easier to treat the primary depressive disorder. A new method of treatment for OSA, the Sullivan continuous positive airway pump (CPAP), raises the theoretical possibility of treating depression by this means as well. Australian and New Zealand Journal of Psychiatry 1992; 26586-591 Speculation about the nature of sleep goes back many centuries. The emerging discipline of sleep medicine has added considerably to our knowledge of sleep and related disorders. Research by pioneers such as Kleitman, Azerinsky and Dement [ 11 has reached fulfilment in the last two decades. with the estab-lishment of research societies, journals and non-in-vasive sleep laboratory studies. Knowledge about the pathophysiology and clinical features of sleep disor-ders has increased exponentially. Environmental factors or physical illness can affect sleep patterns [ 2] ; alternatively, most psychiatric ill-ness leads to secondary sleep disturbance. However the role of primary sleep disorders in causin