title: Nonshared environmental influences on sleep quality: a study of monozygotic twin differences.
abstract: Research has consistently demonstrated that environmental influences are important for explaining the variability in sleep quality observed in the general population. Although there is substantial evidence assessing associations between sleep quality and a host of environmental variables, it is possible that their effects are mediated by genetic influence. A monozygotic twin differences design was used to assess the specific contribution of nonshared environmental influences on sleep quality, whilst controlling for genetic and shared environmental effects in a sample of 380 monozygotic twins (mean age 19.8 years, SD = 1.26, range = 18-22 years). Participants completed the Pittsburgh Sleep Quality Index and questionnaires assessing several candidate "environmental" measures. When controlling for genetic and shared environmental effects, within monozygotic twin-pair differences in sleep quality were associated with within monozygotic twin-pair differences in general health for males (β = 1.56, p < 0.001) and relationship satisfaction for females (β = 1.01, p < 0.05). For the remaining environmental measures the results suggest that these seemingly "environmental" influences are actually in part dependent on genetics and/or the shared environment. These findings give insight into how specific environments affect sleep and the possible mechanisms behind these associations.
authors: Northumbria Centre for Sleep Research, Department of Psychology, School of Life Sciences, Northumbria University, Northumberland Building, Newcastle upon Tyne, UK. nicola.barclay@northumbria.ac.uk.
authors: Nicola L
authors: NL
authors: Barclay
authors: Thalia C
authors: TC
authors: Eley
authors: Daniel J
authors: DJ
authors: Buysse
authors: Barbara
authors: B
authors: Maughan
authors: Alice M
authors: AM
authors: Gregory
mesh_terms: D000293:Adolescent; D004777:Environment; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D008297:Male; D012890:Sleep / Q000235:genetics*; D011795:Surveys and Questionnaires; D014430:Twins, Monozygotic / Q000235:genetics*; D055815:Young Adult