Suicide is one of the most commonly reported causes of death in individuals with eating disorders. However, the mechanisms underlying the suicide and disordered eating link are largely unknown, and current assessments are still unable to accurately predict future suicidal thoughts and behaviors. The purpose of this study is to test the utility of two promising proximal risk factors, sleep quality and agitation, in predicting suicidal ideation in a sample of individuals with elevated suicidal thoughts and behaviors, namely those with eating disorders.

Women (N = 97) receiving treatment at an eating disorder treatment center completed weekly questionnaires assessing suicidal ideation, agitation, and sleep. General linear mixed models examined whether agitation and/or sleep quality were concurrently or prospectively associated with suicidal ideation across 12 weeks of treatment.

There was a significant interaction between within-person agitation and sleep quality on suicidal ideation [B(s.e.) = −0.02(0.01), p < 0.05], such that on weeks when an individual experienced both higher than their average agitation and lower than their average sleep quality, they also experienced their highest levels of suicidal ideation. However, neither agitation nor sleep quality prospectively predicted suicidal ideation.

This study was the first to examine dynamic associations between interpersonal constructs and suicidal ideation in individuals with eating disorders. Results suggest that ongoing assessment for overarousal symptoms, such as agitation and poor sleep quality, in individuals with eating disorders may be warranted in order to manage suicidal ideation among this vulnerable population.

Over half of individuals with eating disorders experience suicidal ideation at some point in their lives, yet few longitudinal studies have examined predictors of ideation in this at-risk group. Moreover, prospective research has focused on relatively distal or trait-level factors that are informative for distinguishing who is most at risk but not when. Little is known about more proximal or state-level risk factors that fluctuate within an individual, which is critical for determining when a person is most likely to engage in suicidal behaviors.

Women (N = 97) receiving treatment for their eating disorder completed questionnaires weekly to assess suicidal ideation and interpersonal constructs (i.e. perceived burdensomeness, thwarted belongingness) theorized to be proximal predictors of suicidal desire. Longitudinal multilevel models were conducted to examine both within- and between-person predictors of suicidal ideation across 12 weeks of treatment.

Statistically significant within-person effects for burdensomeness (β = 0.06; p < 0.001) indicate that when individuals have greater feelings of burdensomeness compared to their own average, they also experience higher suicidal ideation. We did not find any significant influence of thwarted belongingness or the interaction between burdensomeness and belongingness on suicidal ideation.

This study was the first to examine dynamic associations between interpersonal constructs and suicidal ideation in individuals with eating disorders. Results are only partially consistent with the Interpersonal Theory of Suicide and suggest that short-term changes in burdensomeness may impact suicidal behavior in individuals with eating disorders.