Introduction Suicide Represents a Major Worldwide Social and Public Health Problem with about 1 Mil- Lion Deaths in the World

SUICIDE REPRESENTS A MAJOR WORLDWIDE SOCIAL AND PUBLIC HEALTH PROBLEM WITH ABOUT 1 MILLION DEATHS IN THE WORLD EACH YEAR. Suicide is a leading cause of death for young adults. It is among the top 3 causes of death in the population aged 15 to 34 years.1 Suicide risk begins to increase during adolescence.2 Prevalence rates for suicidal ideation among adolescents have been estimated from 11% for severe suicidal ideation to 75% for any degree of suicidal ideation, 3-5 with an average rate of 20% for suicidal ideation and 8% for suicide attempts during the past year. 6,7 Suicidal ideation and suicide attempts are associated with increased risk for completed suicide in the future. The risk factors of suicidal behavior found in previous studies, quite similar to those of completed suicide, are multiple in origin, including biologic, cognitive, psychological, social and family factors.6 A number of studies have consistently reported that adolescents do not get enough sleep and that their sleep patterns are characterized by staying up late.8-11 Adolescents are also at increased risk for many sleep disorders, such as insomnia, daytime sleepiness, chronic nightmares, and delayed sleep phase syndrome.12-14 Most studies have demonstrated that the way adolescents sleep and their tendency to get insufficient sleep result in negative effects on their ability to think and concentrate in school, school performance, behavior, and mood during daytime hours and an increased risk for injuries and accidents, drugs and alcohol use, and circadian sleep disorders. 9-11, 15-17 Given evidence that suicidal behavior begins to increase during adolescence and that adolescents do not get enough sleep and are at risk for many sleep disturbances, a particular question is whether sleep patterns and sleep disturbances are associated with increased risk for adolescent suicidal behavior. Several recent studies have examined the association between sleep disturbances and suicidality among patients with psychiatric disorders, such as major depression, panic disorder and schizophrenia.18-22 Two prospective studies of adults have reported that poor sleep quality and nightmares are significant predictors of completed suicide.23,24 However, there is a virtual absence of information about sleep-suicidality relationships among adolescents. Identifying links between sleep and suicidal behavior among adolescents may therefore be an important step in detecting, treating, or even preventing future suicide. The data analyzed for the current study came from an epidemiologic survey of mental health problems in a sample of 1,362 adolescents attending school in rural China,12,16 where suicide rates are 3 times higher than urban rates.25 The current study was aimed at providing an exploratory examination of the association between sleep and adolescent suicidal behavior (including suicidal ideation and suicide attempts). The specific purposes of the study were (1) to examine the association between sleep duration and suicidal behavior, (2) to examine the association between nightmares and suicidal behavior, and (3) to examine the association between insomnia symptoms and suicidal behavior after controlling for potential confounding effects of demographic variables and depressive symptoms. It was hypothesized that suicidal behavior would be associated with short sleep duration and insomnia symptoms because research has demonstrated the adverse effects of sleep insufficiency and insomnia on behav-