Sleep duration and depressive symptoms: a gene-environment interaction.
OBJECTIVE
We used quantitative genetic models to assess whether sleep duration modifies genetic and environmental influences on depressive symptoms.


METHODS
Participants were 1,788 adult twins from 894 same-sex twin pairs (192 male and 412 female monozygotic [MZ] pairs, and 81 male and 209 female dizygotic [DZ] pairs] from the University of Washington Twin Registry. Participants self-reported habitual sleep duration and depressive symptoms. Data were analyzed using quantitative genetic interaction models, which allowed the magnitude of additive genetic, shared environmental, and non-shared environmental influences on depressive symptoms to vary with sleep duration.


RESULTS
Within MZ twin pairs, the twin who reported longer sleep duration reported fewer depressive symptoms (ec = -0.17, SE = 0.06, P < 0.05). There was a significant gene × sleep duration interaction effect on depressive symptoms (a'c = 0.23, SE = 0.08, P < 0.05), with the interaction occurring on genetic influences that are common to both sleep duration and depressive symptoms. Among individuals with sleep duration within the normal range (7-8.9 h/night), the total heritability (h2) of depressive symptoms was approximately 27%. However, among individuals with sleep duration within the low (< 7 h/night) or high (≥ 9 h/night) range, increased genetic influence on depressive symptoms was observed, particularly at sleep duration extremes (5 h/night: h2 = 53%; 10 h/night: h2 = 49%).


CONCLUSIONS
Genetic contributions to depressive symptoms increase at both short and long sleep durations.
Department of Neurology, University of Washington, Seattle, WA ; UW Medicine Sleep Center, University of Washington, Seattle, WA ; Center for Research on the Management of Sleep Disturbances, University of Washington, Seattle, WA.
Nathaniel F
NF
Watson
Department of Psychology, University of Texas at Austin, Austin, TX.
Kathryn Paige
KP
Harden
Department of Epidemiology, University of Washington, Seattle, WA.
Dedra
D
Buchwald
Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA ; Center for Research on the Management of Sleep Disturbances, University of Washington, Seattle, WA.
Michael V
MV
Vitiello
Division of Sleep Medicine/Department of Medicine and Center for Sleep and Circadian Neurobiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
Allan I
AI
Pack
Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA.
Eric
E
Strachan
Department of Epidemiology, University of Washington, Seattle, WA ; Vietnam Era Twin Registry, VA Epidemiologic Research and Information Center, Seattle, WA.
Jack
J
Goldberg
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003863:Depression / Q000235:genetics* / Q000503:physiopathology / Q000523:psychology*; D004777:Environment; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D012042:Registries; D012890:Sleep / Q000235:genetics / Q000502:physiology*; D013997:Time Factors; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology; D055815:Young Adult
Depression; Dizygotic; Monozygotic; Sleep Duration; Symptoms; Twins