0656 Demographic and Clinical Features of Nocturnal Suicide

Abstract

Abstract Introduction The risk for suicide is greatest at night after adjusting for population wakefulness, possibly due to sleep- and circadian-dependent changes in neurophysiology to promote sleep. Those who die by suicide at night, however, may differ by demographic and/or clinical characteristics from those who die by suicide during the day. Methods An archival analysis of the National Violent Death Reporting System for 2003-2017 identified 77,784 suicide deaths with time of fatal injury. Cases were divided into daytime (5AM to 10:59PM) or nighttime (11PM to 4:59AM) and characterized by age, sex, race, ethnicity, marital status, military service, education, prior diagnosis of an anxiety disorder, bipolar disorder, depression, history of suicidal ideation, PTSD, and schizophrenia, as well as the presence of an opiate or cannabis, and blood alcohol level (BAL) on autopsy. Bidirectional stepwise regression and robust Poisson models characterized significant predictors of nocturnal suicide using incident risk ratios (IRR). Results Nocturnal and daytime suicides differed on all sociodemographic variables. Nocturnal suicides were more prevalent among those with bipolar disorder, PTSD, an elevated BAL, and those who tested positive for cannabis. Stepwise models identified a significant age by BAL interaction. Using adults 35-64 with BAL=0mg/dl as the reference, adults 35-64 with a BAL<80mg/dl had a 46% greater risk of suicide at night, and those with a BAL≥80mg/dl had a 78% greater risk. Individuals 15-34 had a nighttime suicide that was 26% greater with BAL=0mg/dl, 84% greater with BAL<80mg/dl, and 298% greater with BAL≥80mg/dl. Conversely, individuals 65 and older were 27% less likely to die at night with BAL=0mg/dl, while those with a BAL>0mg/dl did not differ from those aged 35-64 with BAL=0mg/dl. The risk of nocturnal suicide was also 17% greater among those with a prior history of suicidal ideation, and 13% less likely among those with documented depression. Conclusion Nocturnal suicide is more prevalent among intoxicated younger adults and those with previous suicidal ideation. However, suicide victims with depression were less likely to die at night. Further research is needed to target suicide prevention efforts at appropriately times for those with mood, substance, and alcohol use disorders. Support (If Any)