Background: Insomnia increases in prevalence with age, is strongly associated with depression, and has been identified as a risk factor for suicide in several studies. The aim of this study was to determine whether insomnia severity varies between those who have attempted suicide (n = 72), those who only contemplate suicide (n = 28), and those who are depressed but have no suicidal ideation or attempt history (n = 35).
Methods: Participants were middle-aged and older adults (age 44-87, M = 66 years) with depression. Insomnia severity was measured as the sum of the early, middle, and late insomnia items from the Hamilton Rating Scale for Depression. General linear models examined relations between group status as the independent variable and insomnia severity as the dependent variable.
Results: The suicide attempt group suffered from more severe insomnia than the suicidal ideation and non-suicidal depressed groups (p < 0.05). Differences remained after adjusting for potential confounders including demographics, cognitive ability, alcohol dependence in the past month, severity of depressed mood, anxiety, and physical health burden. Moreover, greater insomnia severity in the suicide attempt group could not be explained by interpersonal difficulties, executive functioning, benzodiazepine use, or by the presence of post-traumatic stress disorder.
Conclusions: Our results suggest that insomnia may be more strongly associated with suicidal behavior than with the presence of suicidal thoughts alone. Accordingly, insomnia is a potential treatment target for reducing suicide risk in middle-aged and older adults.
Keywords: depression; insomnia symptoms; suicidal ideation; suicide attempt.