title: Nocturnal Wakefulness as a Previously Unrecognized Risk Factor for Suicide.
abstract: Suicide is a major public health problem and the 10th leading cause of death in the United States. The identification of modifiable risk factors is essential for reducing the prevalence of suicide. Recently, it has been shown that insomnia and nightmares significantly increase the risk for suicidal ideation, attempted suicide, and death by suicide. While both forms of sleep disturbance may independently confer risk, and potentially be modifiable risk factors, it is also possible that simply being awake at night represents a specific vulnerability for suicide. The present analysis evaluates the frequency of completed suicide per hour while taking into account the percentage of individuals awake at each hour.
  
  
  
  Archival analyses were conducted estimating the time of fatal injury using the National Violent Death Reporting System for 2003-2010 and the proportion of the American population awake per hour across the 24-hour day using the American Time Use Survey.
  
  
  
  The mean ± SD incident rate from 06:00-23:59 was 2.2% ± 0.7%, while the mean ± SD incident rate from 00:00-05:59 was 10.3% ± 4.9%. The maximum incident rate was from 02:00-02:59 (16.3%). Hour-by-hour observed values differed from those that would be expected by chance (P < .001), and when 6-hour blocks were examined, the observed frequency at night was 3.6 times higher than would be expected by chance (P < .001).
  
  
  
  Being awake at night confers greater risk for suicide than being awake at other times of the day, suggesting that disturbances of sleep or circadian neurobiology may potentiate suicide risk.
authors.affiliation: Behavioral Sleep Medicine Program, Department of Psychiatry, University of Pennsylvania, 3535 Market St, Ste 670, Philadelphia, PA 19104. mperlis@upenn.edu.|Behavioral Sleep Medicine Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia bCenter for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia cSchool of Nursing, University of Pennsylvania, Philadelphia dCenter for the Prevention of Suicide, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia eDivision of Sleep and Chronobiology, Unit for Experimental Psychiatry, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia fMental Illness Research, Education, and Clinical Center of the Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania gCenter for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia hMaster of Population Health Sciences Program, Washington University, St Louis, Missouri iMood and Anxiety Disorders Treatment & Research Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia jDepartment of Psychiatry, University of Arizona, Tucson (current affiliation) kDepartment of Emergency Medicine, University of Alabama School of Medicine, Birmingham (current affiliation) lDepartment of Epidemiology, School of Public Health, University of Alabama, Birmingham (current affiliation).
authors.forename: Michael L
authors.initials: ML
authors.lastname: Perlis
authors.affiliation: Behavioral Sleep Medicine Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia bCenter for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia cSchool of Nursing, University of Pennsylvania, Philadelphia dCenter for the Prevention of Suicide, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia eDivision of Sleep and Chronobiology, Unit for Experimental Psychiatry, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia fMental Illness Research, Education, and Clinical Center of the Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania gCenter for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia hMaster of Population Health Sciences Program, Washington University, St Louis, Missouri iMood and Anxiety Disorders Treatment & Research Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia jDepartment of Psychiatry, University of Arizona, Tucson (current affiliation) kDepartment of Emergency Medicine, University of Alabama School of Medicine, Birmingham (current affiliation) lDepartment of Epidemiology, School of Public Health, University of Alabama, Birmingham (current affiliation).
authors.forename: Michael A
authors.initials: MA
authors.lastname: Grandner
authors.forename: Gregory K
authors.initials: GK
authors.lastname: Brown
authors.forename: Mathias
authors.initials: M
authors.lastname: Basner
authors.affiliation: Behavioral Sleep Medicine Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia bCenter for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia cSchool of Nursing, University of Pennsylvania, Philadelphia dCenter for the Prevention of Suicide, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia eDivision of Sleep and Chronobiology, Unit for Experimental Psychiatry, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia fMental Illness Research, Education, and Clinical Center of the Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania gCenter for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia hMaster of Population Health Sciences Program, Washington University, St Louis, Missouri iMood and Anxiety Disorders Treatment & Research Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia jDepartment of Psychiatry, University of Arizona, Tucson (current affiliation) kDepartment of Emergency Medicine, University of Alabama School of Medicine, Birmingham (current affiliation) lDepartment of Epidemiology, School of Public Health, University of Alabama, Birmingham (current affiliation).
authors.forename: Subhajit
authors.initials: S
authors.lastname: Chakravorty
authors.forename: Knashawn H
authors.initials: KH
authors.lastname: Morales
authors.affiliation: Behavioral Sleep Medicine Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia bCenter for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia cSchool of Nursing, University of Pennsylvania, Philadelphia dCenter for the Prevention of Suicide, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia eDivision of Sleep and Chronobiology, Unit for Experimental Psychiatry, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia fMental Illness Research, Education, and Clinical Center of the Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania gCenter for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia hMaster of Population Health Sciences Program, Washington University, St Louis, Missouri iMood and Anxiety Disorders Treatment & Research Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia jDepartment of Psychiatry, University of Arizona, Tucson (current affiliation) kDepartment of Emergency Medicine, University of Alabama School of Medicine, Birmingham (current affiliation) lDepartment of Epidemiology, School of Public Health, University of Alabama, Birmingham (current affiliation).
authors.forename: Philip R
authors.initials: PR
authors.lastname: Gehrman
authors.affiliation: Behavioral Sleep Medicine Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia bCenter for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia cSchool of Nursing, University of Pennsylvania, Philadelphia dCenter for the Prevention of Suicide, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia eDivision of Sleep and Chronobiology, Unit for Experimental Psychiatry, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia fMental Illness Research, Education, and Clinical Center of the Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania gCenter for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia hMaster of Population Health Sciences Program, Washington University, St Louis, Missouri iMood and Anxiety Disorders Treatment & Research Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia jDepartment of Psychiatry, University of Arizona, Tucson (current affiliation) kDepartment of Emergency Medicine, University of Alabama School of Medicine, Birmingham (current affiliation) lDepartment of Epidemiology, School of Public Health, University of Alabama, Birmingham (current affiliation).
authors.forename: Ninad S
authors.initials: NS
authors.lastname: Chaudhary
authors.forename: Michael E
authors.initials: ME
authors.lastname: Thase
authors.forename: David F
authors.initials: DF
authors.lastname: Dinges
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology* / Q000523:psychology*; D013223:Statistics as Topic; D013405:Suicide / Q000523:psychology* / Q000706:statistics & numerical data*; D013406:Suicide, Attempted / Q000523:psychology* / Q000706:statistics & numerical data*; D014851:Wakefulness; D055815:Young Adult