title: Early Blood Lead Levels and Sleep Disturbance in Preadolescence.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Four community-based elementary schools in Jintan City, China.
  
  
  METHODS
  1,419 Chinese children.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Nursing, University of Pennsylvania, Philadelphia, PA.
authors.forename: Jianghong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Shandong University School of Public Health, Jinan, China.
authors.forename: Xianchen
authors.initials: X
authors.lastname: Liu
authors.affiliation: School of Nursing, University of Pennsylvania, Philadelphia, PA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Pak
authors.affiliation: School of Nursing, University of Pennsylvania, Philadelphia, PA.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Xinhua Hospital, MOE-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Jiaotong University School of Medicine, China.
authors.forename: Chonghuai
authors.initials: C
authors.lastname: Yan
authors.affiliation: School of Nursing, University of Pennsylvania, Philadelphia, PA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Pinto-Martin
authors.affiliation: Division of Sleep and Chronobiology, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: David
authors.initials: D
authors.lastname: Dinges
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D010290:Parents; D015995:Prevalence; D012111:Residence Characteristics; D018570:Risk Assessment; D012574:Schools; D012894:Sleep Stages / Q000502:physiology; D012893:Sleep Wake Disorders / Q000097:blood* / Q000453:epidemiology / Q000503:physiopathology*; D011795:Surveys and Questionnaires
chemical_list: D007854:Lead
keywords: blood lead levels; daytime sleepiness; insomnia; lead exposure; sleep