NOCTURNAL WAKEFULNESS AND SUICIDE RISK REVISITED: AN ANALYSIS OF THE NATIONAL VIOLENT DEATH REPORTING SYSTEM 2003 TO 2017

Abstract

Suicide is the 10th leading cause of death in the United States, and poor sleep contributes to suicide risk. Part of this risk occurs at night when individuals are awake in opposition to their circadian rhythms. This study replicates and expands on prior investigations of nocturnal wakefulness as a suicide risk factor. Data on 78,647 suicides between 2003 to 2017 were extracted from the National Violent Death Reporting System and tabulated by time of fatal injury, whether the data had been previously analyzed (2003-2010) or new (2011-2017), sociodemographic factors, and alcohol or marijuana intoxication. Data were matched with estimates of population wakefulness from the American Time Use Survey. Robust Poisson regression models then estimated the hourly incident risk ratio for suicide after adjusting for population wakefulness. Although suicides peaked at noon, the incident risk for suicide was highest at night (IRR 5.18 [3.21, 8.36]) at 3AM. Results did not differ between previously analyzed and new data. Moreover, there was an age by blood alcohol level interaction in nighttime suicide risk such that risk increased with younger age and higher blood alcohol levels. The behavioral risk for suicide appears highest at night and is increased among younger adults and those with greater alcohol intoxication. Part of this risk occurs at night when individuals experience irregularities in their circadian rhythms that may result in disturbances relating to executive function and behavior.