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.