Study Objectives: A growing body of research indicates that sleep disturbances may be specifically linked to suicidal behaviors. It remains unclear, however, whether this link is largely explained by depressive symptoms. The present study investigated the relationship between suicidality, depression, and sleep complaints in a clinical outpatient setting. Design and Setting: Upon admission, 176 outpatients completed measures on sleep disturbances, suicidal symptoms, and depression. Several sleep disturbances were evaluated with regard to suicidal ideation, including insomnia, nightmares, and sleep-related breathing symptoms. Measurements and Results: Regression analyses revealed that insomnia and nightmare symptoms were associated with both depressive symptoms and suicidality, Sleep-related breathing symptoms were associated with depressive symptoms, but did not show an association with suicidal ideation. After controlling for depressive symptoms, only nightmares demonstrated an association with suicidal ideation. This relationship emerged as a nonsignificant trend (P = .06). Nightmares were particularly associated with suicidality among women compared with men. Posthoc analyses revealed that, after controlling for sex and depressive symptoms, nightmare symptoms were significantly associated with suicidality (P = .04). Conclusions: Although insomnia and nightmares were significantly associated with depressive and suicidal symptoms, after controlling for additional variables, such as depression and sex, only nightmares remained associated with suicidality. This association was slightly stronger among women compared with men.
