Longitudinal associations of nightmare frequency and nightmare distress with suicidal behavior in adolescents: mediating role of depressive symptoms.

STUDY OBJECTIVES: Nightmares are a significant risk factor of suicidal behavior. This study examined the longitudinal associations of nightmare frequency and distress with suicidal thought (ST), suicide plan (SP), and suicide attempt (SA) and mediating role of depressive symptoms in adolescents. METHODS: A total of 6,923 adolescents who participated in the 1-year follow-up of Shandong Adolescent Behavior & Health Cohort were included for the analysis. Participants completed a self-administered questionnaire to assess nightmares, sleep duration, insomnia, depressive symptoms, substance use, prior suicidal behavior, and family demographics in November-December in 2015. One year later, a follow-up survey was conducted to ask participants to report their depressive symptoms and suicidal behaviors. RESULTS: Of the sample, 26.2% reported having frequent nightmares (at least twice/month) at baseline, and 10.0%, 3.6%, and 2.7% reported having ST, SP, and SA over 1-year follow-up. The rates of subsequent ST, SP, and SA all significantly increased with baseline nightmare frequency and distress. Path analyses showed that depressive symptoms played a significant mediating role in the associations of frequent nightmares and elevated nightmare distress with ST, SP, and SA before and after adjusting for adolescent and family covariates and prior suicidal behavior. CONCLUSIONS: Suicidal risk increased with nightmare frequency and distress among adolescents. The association between nightmares and suicidal behavior was at least partially mediated by depressive symptoms. Assessing and intervening nightmares and depressive symptoms associated with nightmares may have important implications for preventing adolescent suicidal behavior.

Early Blood Lead Levels and Sleep Disturbance in Preadolescence.

STUDY OBJECTIVES: Little is known about the effect of lead exposure on children's sleep. This study examined the association between blood lead levels (BLL) and sleep problems in a longitudinal study of children. SETTING: Four community-based elementary schools in Jintan City, China. PARTICIPANTS: 1,419 Chinese children. MEASUREMENT AND RESULTS: BLL were measured when children were aged 3-5 y, and sleep was assessed at ages 9-13 y. Sleep was assessed by both parents' report, using the Children's Sleep Habits Questionnaire (CSHQ), and children's report, using an adolescent sleep questionnaire. A total of 665 children with complete data on BLL and sleep at both ages were included in the current study. Mean age of the sample at BLL assessment was 4.74 y (standard deviation [SD] = 0.89) and at sleep assessment was 11.05 y (SD = 0.88). Mean BLL was 6.26 µg/dL (SD = 2.54). There were significant positive correlations between BLL and 3 CSHQ subscales: Sleep onset delay (r = 0.113, P < 0.01), sleep duration (r = 0.139, P < 0.001), and night waking (r = 0.089, P < 0.05). Excessive daytime sleepiness (EDS) (26.1% versus 9.0%, P < 0.001) and use of sleeping pills (6.5% versus 1.8%, P = 0.03) were more prevalent in children BLL ≥ 10.0 µg/dL than in those children BLL < 10.0 µg/dL. After adjusting for demographics, BLL ≥ 10.0 µg/dL was significantly associated with increased risk for insomnia symptoms (odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.03-3.95) and EDS (OR = 2.90, 95% CI = 1.27-6.61). CONCLUSION: The findings indicate that elevated blood lead levels in early childhood are associated with increased risk for sleep problems and excessive daytime sleepiness in later childhood.

Sleep problems, fatigue, and cognitive performance in Chinese kindergarten children.

OBJECTIVE: To examine sleep problems and fatigue and their associations with cognitive performance in Chinese kindergarten children. STUDY DESIGN: A cross-sectional analysis of baseline data from Jintan Child Cohort Study was conducted, which includes a cohort of 1656 kindergarten children in Jintan City, Jiangsu Province, China. The sample used in the current study consisted of 1385 children (44.8% girls, mean age 5.72 [SD = 0.42] years) for whom data on sleep problems or cognitive performance were available. Child Behavior Checklist was used to measure child sleep problems and fatigue, and Wechsler Preschool and Primary Scale of Intelligence-Revised was used to assess child IQ. RESULTS: Sleep problems were prevalent, ranging from 8.9% for difficulty maintaining sleep to 70.5% for unwilling to sleep alone. Other reported sleep problems were difficulty initiating sleep (39.4%), nightmares (31.6%), sleep talking (28%), sleeping less (24.7%), and sleep resistance (23.4%). Fatigue was also prevalent, with 29.6% of children reported to be overtired and 12.6% lack of energy. Children with difficulty maintaining sleep, sleep talking, sleep resistance, or nightmares scored 2-3 points lower in full IQ than children without sleep problems. Children reported to have fatigue scored 3-6 points lower in full IQ than those children without fatigue. CONCLUSIONS: Sleep problems and fatigue are prevalent in Chinese kindergarten children. Furthermore, sleep problems and fatigue are associated with poor cognitive performance.