Depression is differently associated with sleep measurement in obstructive sleep apnea, restless leg syndrome and periodic limb movement disorder.

Depression causes sleep disturbance and is associated with various sleep-related disorders. However, how depression affects the symptomatic presentation of different sleep-related disorders is unclear. In this study, we investigated the sleep parameters of different sleep-related disorders between depressive and non-depressive patients. A total of 785 patients underwent polysomnography in a mental hospital from Jan 2012 to Jun 2013. We first analyzed variables between the depressive and non-depressive groups. The patients were then divided into four groups: obstructive sleep apnea (OSA, n = 339), restless leg syndrome (RLS, n = 51), periodic limb movement disorder (PLMD, n = 58) and comorbid group (OSA and RLS, n = 46). We next compared sleep measures between the depressive and non-depressive subjects within each groups. The patients with OSA and depression were significantly associated with a higher periodic limb movement index. Significantly more patients with RLS patients and depression had initial insomnia complaints. However, significantly more patients with PLMD and depression middle insomnia. Compared with non-depressive population, depressive patients had higher comorbidity with RLS and PLMD. Depression may have different association with the sleep parameters in different sleep-related disorders. Further investigations are needed to investigate how these findings may affect patients' awareness and clinicians' diagnosis and management of sleep-related disorders.