title: Etiologies of associations between childhood sleep and behavioral problems in a large twin sample.
abstract: OBJECTIVE
  To examine the etiologies of covariation of childhood sleep problems and other behavioral/emotional problems in young children.
  
  
  METHODS
  The parents of more than 6,000 twin pairs provided information on their twins' anxiety, conduct, and hyperactivity at ages 3, 4, and 7 by completing the Strengths and Difficulties Questionnaire. Information on sleep problems was obtained at age 3/4.
  
  
  RESULTS
  Phenotypic correlations in preschool years between sleep problems and anxiety, conduct, and hyperactivity ranged from 0.17 to 0.22. These correlations were largely due to shared environmental factors (0.72-0.96) and less to heredity (0.05-0.26) and nonshared environment (0.00-0.06). Sleep problems at age 3/4 years predicted at age 7 years anxiety (beta =.12, p <.001), conduct problems (beta =.09, p <.001), and hyperactivity (beta =.07, p <.001), after accounting for stability of these problems. These predictive associations were also mainly mediated by shared environment (0.16-0.91), although genetic (0.02-0.84) and nonshared environmental (-0.03-0.09) factors were also influential.
  
  
  CONCLUSIONS
  The modest associations between early sleep problems and later behavioral/emotional problems are largely accounted for by common psychosocial risk factors. Further research on which specific risks may mediate these connections is needed.
authors.affiliation: Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, England. a.gregory@iop.kcl.ac.uk
authors.forename: Alice M
authors.initials: AM
authors.lastname: Gregory
authors.forename: Thalia C
authors.initials: TC
authors.lastname: Eley
authors.forename: Thomas G
authors.initials: TG
authors.lastname: O'Connor
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
mesh_terms: D000704:Analysis of Variance; D002648:Child; D002653:Child Behavior Disorders / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D002675:Child, Preschool; D015897:Comorbidity; D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008957:Models, Genetic; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D006113:United Kingdom / Q000453:epidemiology