RESUMEN
BACKGROUND: Patients suffering from treatment-resistant depression (TRD) are at risk of suicide. Sleep and circadian rhythm alterations are widely recognized as core symptoms of major depressive disorder and are associated with suicidal ideation. Thus, sleep and circadian rhythm alterations may be targeted to prevent suicide. METHODS: Patients were recruited from a prospective cohort of the French network of TRD expert centers. Mood, sleep and circadian rhythms were assessed at baseline; suicidal risk was assessed both at baseline and during a one-year follow-up with standardized subjective questionnaires. RESULTS: Excessive daytime sleepiness (adjusted odds ratio aOR = 1.7(1-3.3), p = 0.04) and daytime dysfunction (aOR = 1.81(1.16-2.81), p = 0.0085) increased the risk of suicidal thoughts over the one-year follow-up period in patients with TRD after adjustment on age, gender, depression, trauma, anxiety, impulsivity, current daily tobacco smoking and body mass index. Hypnotics intake is associated with a reduced risk of suicidal ideation at one-year follow-up after the same adjustments (OR = 0.73(0.56-0.95), p = 0.019). Other associations between sleep quality or circadian rhythms and suicidal ideations at either baseline or one year did not remain significant in multivariate analyses after the same adjustments. LIMITATIONS: Sleep assessments were based on self-reported questionnaires rather than objective measures. CONCLUSIONS: Daytime sleepiness and dysfunction are predictors of suicidal ideations, whereas hypnotics intake is associated with a reduced risk of suicidal ideations. Diurnal symptoms of sleep disturbances are therefore red flags to target for preventing suicide in depressed patients, and hypnotics seem efficient in preventing suicide for patients with TRD.