SLEEP DURATION AND BODY MASS INDEX IN TWINS
Sleep Duration and Body Mass Index in Twins: A Gene-Environment Interaction
Nathaniel F. Watson, MD, MSc1,2,3; Kathryn Paige Harden, PhD6; Dedra Buchwald, MD4; Michael V. Vitiello, PhD3,5; Allan I. Pack, MB ChB, PhD7; David S. Weigle, MD4; Jack Goldberg, PhD8
1Department of Neurology, University of Washington, Seattle, WA; 2UW Medicine Sleep Center, University of Washington, Seattle, WA; 3Center for Research on the Management of Sleep Disturbances, University of Washington, Seattle, WA; 4Department of Medicine, University of Washington, Seattle, WA; 5Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA; 6Department of Psychology, University of Texas at Austin, Austin, TX; 7Division of Sleep Medicine/Department of Medicine and Center for Sleep and Circadian Neurobiology, University of Pennsylvania School of Medicine, Philadelphia, PA; 8Department of Epidemiology, University of Washington, and Vietnam Era Twin Registry, VA Epidemiologic Research and Information Center, Seattle, WA
To examine whether sleep duration modifies genetic and environmental influences on body mass index (BMI).
Genotype-environment interaction twin study.
University of Washington Twin Registry.
Patients or Participants:
A population-based sample of US twins (1,088 pairs, 604 monozygotic, 484 dizygotic; 66% female; mean age = 36.6 yr, standard deviation (SD) = 15.9 yr).
Measurements and Results:
Participants self-reported information on height, weight, and sleep. Mean BMI was calculated as 25.3 kg/m2 (SD = 5.4) and mean habitual sleep duration was 7.2 hr/night (SD = 1.2). Data were analyzed using biometric genetic interaction models. Overall the heritability of sleep duration was 34%. Longer sleep duration was associated with decreased BMI (P < 0.05). The heritability of BMI when sleep duration was < 7 hr (h2 = 70%) was more than twice as large as the heritability of BMI when sleep duration was ≥ 9 hr (h2 = 32%); this interaction was significant (P < 0.05).
Shorter sleep duration is associated with increased BMI and increased genetic influences on BMI, suggesting that shorter sleep duration increases expression of genetic risks for high body weight. At the same time, longer sleep duration may suppress genetic influences on body weight. Future research aiming to identify specific genotypes for BMI may benefit by considering the moderating role of sleep duration.
Watson NF; Harden KP; Buchwald D; Vitiello MV; Pack AI; Weigle DS; Goldberg J. Sleep duration and body mass index in twins: a gene-environment interaction. SLEEP 2012;35(5):597-603.