Sleep disturbance and suicidality in patients with bipolar disorders – The mediating role of rumination and impulsivity

Forrest Tin Wai Cheung, Hongliang Feng, Lai Yan Ho, Binbin Lei, Ngan Yin Chan, Joey Wing Yan Chan, Steven Wai Ho Chau, Jihui Zhang, Yun Kwok Wing, Shirley Xin Li

Abstract

Introduction: Individuals with bipolar disorders (BAD) often complain of having insomnia and nightmares. Such sleep disturbance has been shown to be associated with an increased risk for suicidality. Some psychological factors observed in BAD patients, namely rumination and impulsivity, are thought to be exacerbated by sleep disturbance. The present study aimed to examine whether rumination and impulsivity mediated the association between sleep disturbance and suicidal ideation in a sample of BAD patients.

Materials and Methods: One hundred and seven BAD patients (Mean age = 46.6 years, SD = 11.6, female = 73%) were recruited from local psychiatric outpatient clinics and completed a battery of self-report questionnaires. The diagnosis was ascertained by the Mini-International Neuropsychiatric Interview (MINI). Sleep disturbance was assessed by Insomnia Severity Index (ISI) for insomnia and Nightmare Distress Questionnaire (NDQ) for nightmares. Rumination and trait impulsivity were assessed by Ruminative Response Scale (RRS) and Barratt Impulsiveness Scale (BIS-11), respectively. Suicidal ideation was assessed by Beck’s Scale for Suicidal Ideation (BSSI). A series of mediation models were tested with regression analysis with the significance of indirect effect tested by bootstrapping 5000 samples.

Results: Within our sample, 32.7% reported having clinical insomnia (defined as >= 15 on ISI) and 18.8% reported experiencing frequent nightmares (at least once per week) in the past three months. Suicidal ideation was significantly correlated with insomnia (r = .487, p < .001) and nightmares ( r = .384, p < .001). A positive correlation between rumination and impulsiveness was found (r = .496, p < .001). There was a significant mediation effect of insomnia on suicidal ideation through rumination (ab = .270, 95% CI (.157, .405], PM = .627) and through impulsivity (ab = .100, 95% CI (.016, .206], PM = .233). A significant mediation effect of nightmares on suicidal ideation was also found through rumination (ab = .368, 95% CI (.191, .574], PM = .693) and impulsivity (ab = .124, 95% CI (.008, .267], PM = .235).

Conclusion: Both insomnia and nightmares are associated with an increase in suicidal ideation in BAD patients. Our data suggest that these associations are mediated by both rumination and impulsivity, where rumination overall have greater mediating effects. Our findings suggest targeting rumination as a possible pathway in treatment strategies and support the need for sleep-focused intervention in suicide risk prevention and intervention in bipolar patients.

Recommended citation: Cheung, F. T. W., Feng, H., Ho, L. Y., Lei, B., Chan, N. Y., Chan, J. W. Y., ... & Li, S. X. (2019). Sleep disturbance and suicidality in patients with bipolar disorders-the mediating role of rumination and impulsivity. Sleep Medicine, 64, S70.