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Sleep and timing of death by suicide among U.S. Veterans 2006-2015: analysis of the American Time Use Survey and the National Violent Death Reporting System.

STUDY OBJECTIVES
Suicide is a top public health priority, and U.S. Veterans are recognized to be at particularly elevated risk. Sleep disturbances are an independent risk factor for suicide; recent empirical data suggest that nocturnal wakefulness may be a key mechanism underlying this association. Given higher rates of sleep disturbances among U.S. Veterans compared with civilians, we examined associations between nocturnal wakefulness and timing of death by suicide in U.S. Veterans and civilians to determine whether temporal suicide patterns differed.


METHODS
The American Time Use Survey and the National Violent Death Reporting System were analyzed (2006-2015) to determine whether sleep and temporal suicide patterns differed between age-stratified groups (18-39, 40-64, and ≥65) of U.S. Veterans and civilians. Observed temporal suicide patterns were reported and standardized incidence ratios (SIRs) calculated to compare the percentage of suicides observed with those expected, given the proportion of the population awake, across clock hours.


RESULTS
The raw proportion of Veteran suicides peaks between the hours of 1000-1200; however, the peak prevalence of suicide after accounting for the population awake is between 0000 and 0300 hr (p < .00001, ϕ = .88). The highest SIR was at midnight; U.S. Veterans were eight times more likely to die by suicide than expected given the population awake (SIR = 8.17; 95% CI = 7.45-8.94).


CONCLUSIONS
Nocturnal wakefulness is associated with increased risk for suicide in U.S. Veterans. Overall patterns of observed suicides by clock hour were similar between U.S. Veterans and civilians. However, Veteran-specific SIRs suggest differences in magnitude of risk by clock hour across age groups. Future research examining female and Post-9/11 U.S. Veterans is warranted.