Actigraphy-Measured Sleep/Wake Characteristics Associated with Suicidal Ideation in Older Adults Who Have Depression and High Suicide Risk.

Objective: The aim of this study was to identify sleep/wake characteristics associated with suicidal ideation (SI) severity among older adults who are at risk for suicide. Methods: This 6-week observational study examined associations between weekly actigraphy-derived sleep/wake measures and SI severity (Beck Scale for Suicidal Ideation [SSI]). The sample (n = 30; 83% female; average age = 62 years), enrolled April 2021 through March 2023, self reported a physician diagnosis of DSM-5 major depressive disorder with an episode in the last 6 months and also had either recent active SI or a past suicide attempt. Weekly sleep/wake measures included sleep duration, fragmentation, and 2 rhythm variables (interdaily stability and relative amplitude). Primary analyses used age- and sex-adjusted repeated-measure linear mixed models, 1 model per sleep/wake variable, to assess associations between weekly sleep/ wake and SI reported at week's end. We examined if associations of sleep/wake factors with SI were independent of depression severity (Patient Health Questionnaire-8 scores). Results: Longer sleep duration, greater interdaily stability, and higher relative amplitude were associated with lower SI (eg, for each standard deviation higher interdaily stability, SSI scores were an estimated 1.4 points lower [P = .005]). After adjusting for depression severity, both sleep/wake rhythm variables remained significantly associated with SI, whereas the association between sleep duration and SI severity was attenuated by >80%. Conclusion: In this sample, sleep/wake rhythm disruption (but not sleep duration or fragmentation) related to SI independent of depression severity. Targeting disruptions in sleep/wake rhythms may be an important avenue for future trials of sleep medicine approaches to reduce SI in older adults.