Nightmares and suicide: predicting risk in depression.

BACKGROUND: There is growing evidence of an association of a number of subjective and objective sleep parameters (especially nightmares) and elevated suicidal risk in different clinical populations as well as in the general populations. SUBJECTS AND METHODS: This is a cross-sectional naturalistic study of 52 inpatients (28 females and 24 males, aged from 24 to 75 years) meeting criteria for a current depressive episode within Recurrent Depressive Disorder (RDD) or Bipolar Disorder (BD) according to ICD-10. All patients were evaluated with the Hamilton Depression Rating Scale (HDRS), followed by a direct interview about their dreams' content and emotional charge, as well as about suicidal thoughts and plans or previous attempts. RESULTS: Patients with RDD suffered significantly more frequently from nightmares than those with BD, p<0.05. Within the RDD group, experiencing nightmares was associated with significantly higher scores on the HDRS suicide risk item (2.36 vs 1.00), higher frequency of suicide attempts (35% vs 6%), and lower likelihood for lack of detectable suicide risk (21% vs 81%), p<0.05. These differences were not explained by significant difference in the severity of depressive symptoms (28.00 vs 24.75, p=0.16). We were unable to detect such differences in the bipolar subgroup. No gender influences on the association of nightmares and suicidal risk were observed. CONCLUSIONS: Depressed patients suffering from nightmares showed significantly higher suicide risk. Depression appeared to be a stronger risk factor for suicidal behavior when accompanied with nightmares. This was only valid for unipolar depression, while the results concerning bipolar depression were inconclusive.