title: Heritability of insomnia symptoms in youth and their relationship to depression and anxiety.
abstract: OBJECTIVE
  Insomnia is a highly prevalent sleep disorder yet little is known about the role of genetic factors in its pathophysiology. The aim of this study was to examine the relative contributions of genetic and environmental factors in explaining variability in insomnia symptoms.
  
  
  METHODS
  Traditional twin design.
  
  
  METHODS
  Academic medical center.
  
  
  METHODS
  1412 twin pairs aged 8-16 years (48.8% MZ, 47.2% DZ, 4.0% indeterminate).
  
  
  METHODS
  None.
  
  
  RESULTS
  Ratings of insomnia symptoms, depression, and overanxious disorder were made by trained interviewers based on DSM-III-R criteria. ACE models were conducted using Mx statistical software. Insomnia symptoms were prevalent in this sample based both on parental (6.6%) and youth (19.5%) reports. The overall heritability of insomnia symptoms was modest (30.7%), with the remaining variance attributed to unique environmental effects. There was no evidence of sex differences in the prevalence of insomnia symptoms or in the contribution of genetic and environmental effects. In multivariate models, there was support for insomnia-specific unique environmental effects over and above overlapping effects with depression and overanxious disorder, but no evidence for insomnia-specific genetic effects.
  
  
  CONCLUSIONS
  Genetic factors play a modest role in the etiology of insomnia symptoms in 8-16 year-olds. These effects overlap with the genetics of depression and overanxious disorder. Further work is needed to determine which genes confer risk for all three disorders.
authors: Department of Psychiatry & Penn Sleep Center, University of Pennsylvania, 3535 Market Street, Suite 670, Philadelphia, PA 19104, USA. gehrman@upenn.edu
authors: Philip R
authors: PR
authors: Gehrman
authors: Lisa J
authors: LJ
authors: Meltzer
authors: Melisa
authors: M
authors: Moore
authors: Allan I
authors: AI
authors: Pack
authors: Michael L
authors: ML
authors: Perlis
authors: Lindon J
authors: LJ
authors: Eaves
authors: Judy L
authors: JL
authors: Silberg
mesh_terms: D000293:Adolescent; D001007:Anxiety / Q000209:etiology / Q000235:genetics*; D002648:Child; D003863:Depression / Q000209:etiology / Q000235:genetics; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D012737:Sex Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000209:etiology / Q000235:genetics* / Q000523:psychology; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology