A Longitudinal Twin and Sibling Study of Associations Between Insomnia and Depression Symptoms in Young Adults

Sleep. 2016 Nov 1;39(11):1985-1992. doi: 10.5665/sleep.6228.

Abstract

Study objectives: To estimate genetic and environmental influences on the associations between insomnia and depression symptoms concurrently and longitudinally.

Methods: Behavioral genetic analyses were conducted on data from the British longitudinal G1219 twin/sibling study. One thousand five hundred fiftysix twins and siblings participated at Time 1 (mean age = 20.3 years, SD = 1.76). Eight hundred sixty-two participated at Time 2 (mean age = 25.2 years, SD = 1.73 years). Participants completed the Insomnia Symptoms Questionnaire and the Short Mood and Feelings Questionnaire to assess symptoms of insomnia and depression respectively.

Results: Genetic effects accounted for 33% to 41% of the variance of the phenotypes. The phenotypic correlations were moderate (r = 0.34 to r = 0.52). The genetic correlations between the variables were high (0.73-1.00). Genetic effects accounted for a substantial proportion of the associations between variables (50% to 90%). Non-shared environmental effects explained the rest of the variance and covariance of the traits.

Conclusions: While genetic effects play a modest role in insomnia and depression symptoms separately, they appear to play a more central role in concurrent and longitudinal associations between these phenotypes. This should be acknowledged in theories explaining these common associations.

Keywords: depression; genetics; insomnia; longitudinal; twins.

Publication types

  • Twin Study

MeSH terms

  • Adolescent
  • Adult
  • Depression / diagnosis
  • Depression / etiology*
  • Depression / genetics
  • Diseases in Twins / diagnosis
  • Diseases in Twins / etiology*
  • Diseases in Twins / genetics
  • Diseases in Twins / psychology
  • Environment
  • Female
  • Genetic Predisposition to Disease
  • Humans
  • Longitudinal Studies
  • Male
  • Phenotype
  • Psychiatric Status Rating Scales
  • Risk Factors
  • Siblings
  • Sleep Initiation and Maintenance Disorders / diagnosis
  • Sleep Initiation and Maintenance Disorders / etiology*
  • Sleep Initiation and Maintenance Disorders / genetics
  • Sleep Initiation and Maintenance Disorders / psychology
  • Surveys and Questionnaires
  • Twins / genetics
  • Young Adult