The relationship of person-specific eveningness chronotype, greater seasonality, and less rhythmicity to suicidal behavior: A literature review

Background: Epidemiological data have demonstrated seasonal and circadian patterns of suicidal deaths. Several reviews and meta-analyses have confirmed the relationship between sleep disturbance and suicidality. However, these reviews/meta-analyses have not focused on seasonal and circadian dysfunction in relation to suicidality, despite the common presence of this dysfunction in patients with mood disorders. Thus, the current literature review analyzed studies investigating person-specific chronotype, seasonality, and rhythmicity in relation to suicidal thoughts and behaviors. Methods: Study authors reviewed articles related to individual-level chronotype, seasonality, and rhythmicity and suicidality that were written in English and not case reports or reviews. Results: This review supports a relationship between an eveningness chronotype, greater seasonality, and decreased rhythmicity with suicidal thoughts and behaviors in those with unipolar depression, as well as in other psychiatric disorders and in children/adolescents. Limitations: These findings need to be explored more fully in mood disordered populations and other psychiatric populations, in both adults and children, with objective measurement such as actigraphy, and with chronotype, seasonality, and rhythmicity as well as broader sleep disturbance measurement all included so the construct(s) most strongly linked to suicidality can be best identified. Conclusions: Eveningness, greater seasonality, and less rhythmicity should be considered in individuals who may be at risk for suicidal thoughts and behaviors and may be helpful in further tailoring assessment and treatment to improve patient outcome.