Portland State University. Department of Psychology
Term of Graduation
Date of Publication
Master of Science (M.S.) in Psychology
1 online resource (
Suicide rates in the United States have increased almost 30% since 1999 (Centers for Disease Control and Prevention, 2018), making it the tenth leading cause of death in the country (Xu et al., 2018). This problem is especially prominent for veterans of the U.S. Armed Forces, as veterans comprise 8.5% of the U.S. population, yet they account for 18% of all deaths by suicide (Office of Suicide Prevention, 2016). These increasing rates have spurred the need for a better understanding of suicide risk, especially for this high-risk group. Previous research has focused mostly on chronic risk factors, which are useful for identifying who from a population may be more likely to engage in suicidal behaviors, but do not shed light on who may be imminently engaging in suicidal behavior, as would acute warning signs. While it is important to understand what factors affect risk globally, the relationship between more proximal factors needs to be better understood to allow for more targeted and effective risk management. Agitation, a state of mental anguish and emotional overarousal, has emerged as a potential warning sign for suicide (e.g. Rogers, Ringer, & Joiner, 2016), but the stability of agitation over time has yet to be examined. The present study investigated the stability and temporal relationship between two acute warning signs for suicide, agitation and sleep quality, by testing two cross-lagged panel models. Cross-lagged panel models allow for a test of stability and temporal precedence, a necessary condition to establish causality, between two variables. Temporal precedence can be inferred from a comparison of magnitude of the cross-paths, or the time-lagged paths between the baseline of one variable to the follow-up of the other. This thesis utilized a sample of employed post-9/11 veterans who were all either separated active duty, separated from the National Guard or Reserves, or still active in the National Guard or Reserves. Veterans were recruited from 35 different organizations as part of the larger Study for the Employment Retention of Veterans (SERVe; Hammer et al., 2017). Veterans (N = 497) completed the baseline survey and a follow-up survey 3 months later. The sample was mostly white (86%), male (88.5%), had been separated from the military and average of 6.20 years (SD = 3.51), and most had deployed at least once (87.9%). Two cross-lagged panel models were computed to investigate the associations between agitation and perceived sleep quality (model 1) and agitation and insomnia symptoms (model 2). Results indicated that agitation was stable over a three-month period (e.g., model 1, b*= .708, SEb = .039, p < .001), as were sleep disturbances (e.g., model 1, b*= .532, SEb = .044, p < .001). Results of two cross-lagged panel models suggested that agitation temporally precedes sleep quality and insomnia symptoms. This finding provides one possible explanation for why veterans experience greater sleep disturbances than their civilian counterparts (Troxel et al., 2015). Additionally, these findings suggest the importance of considering mental health related factors, like agitation, when treating sleep disturbances. One possible implication of these findings is that when veterans seek help for sleep disturbances, this may be used an opportunity to screen for agitation and suicide risk. This may help identify veterans who are at a greater risk for suicide but would not usually seek mental health care for reasons like mental health stigma (Britt et al., 2008). The findings of the present thesis inform future prevention and intervention efforts regarding veteran suicide risk by establishing this temporal association between agitation and sleep disturbances.
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Denning, Emily Catherine, "An Investigation of the Temporal Relationship between Agitation and Sleep Disturbances" (2020). Dissertations and Theses. Paper 5585.