Circadian Pattern of Deaths Due to Suicide in Intoxicated Alcohol-Dependent Individuals

Objective: Alcohol intoxication and dependence are risk factors for suicide, a leading cause of death in the United States. We examined the hours of peak and nadir in completed suicides over a 24-hour period among intoxicated, alcohol-dependent individuals. We also evaluated suicide-related factors associated with intoxication at different times of the day.

Methods: We analyzed cross-sectional data from the 2003-2010 National Violent Death Reporting System provided by 16 US states. In the primary database, the deceased individuals’ alcohol-dependent status was classified as "yes" or "no or unknown." We restricted the analysis to alcohol-dependent individuals with alcohol level data available (N = 3,661). The primary outcome measure was the reported time of death. Secondary outcome measures were predisposing and injury-related factors. Individuals were classified on the basis of their blood alcohol level (BAL) as heavy drinking (BALH [≥ 80 mg/dL]) or non-heavy drinking (BALO [< 80 mg/dL]). The time of injury was divided into 1-hour bins, which were used to compute the incidence of suicide over 24 hours. We also evaluated the association between clinical factors and BALH for each of six 4-hour time periods beginning at 00:01 hours.

Results: The majority (73.4%) of individuals showed evidence of alcohol consumption prior to committing suicide. BALH was observed in 60.7% of all individuals. Peak incidences in suicide were identified at 21:00 for BALH and 12:00 for BALO, with nadirs at 05:00 and 03:00 hours, respectively. In a multivariable analysis, between 20:01 and 00:00 hours, BALH was associated with more risk and protective factors than BALO.

Conclusions: Identifying critical times and associated risk factors for suicidal behavior may contribute to suicide prevention efforts in intoxicated alcohol-dependent individuals.