title: Heritability of morningness-eveningness and self-report sleep measures in a family-based sample of 521 hutterites.
abstract: Individual variation in the phase and amplitude of human circadian rhythms is well known, but the impact of heritable factors on such variation is less clear. We estimated the narrow-sense heritability for selected circadian and sleep timing, quality, and duration measures among related members of the Hutterites, an endogamous, religious community (n=521 participants). "Morningness-eveningness" (M/E), a stable trait reflecting circadian phase, was evaluated using the Composite Scale (CS). Subjective sleep measures were assessed using the Sleep Timing Questionnaire. Initial analyses reconfirmed the impact of age on M/E. Previously reported correlations between M/E scores and the sleep measures were also noted, demonstrating the construct validity of the questionnaires among the participants. Following corrections for age, gender, and colony of residence, significant narrow-sense heritability was noted for M/E (23%). The heritability for subjective sleep measures (related to timing, duration, and quality) were statistically significant for all but one variable, and varied between 12.4% and 29.4%. Thus, significant heritable influences on human circadian phase and subjective sleep indices can be detected through family-based studies. In view of the impact of circadian malfunction on human health, it may be worthwhile to map genetic factors impacting circadian and sleep variation.
authors.affiliation: Department of Statistics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
authors.forename: Lambertus
authors.initials: L
authors.lastname: Klei
authors.forename: Patrick
authors.initials: P
authors.lastname: Reitz
authors.forename: Mary
authors.initials: M
authors.lastname: Miller
authors.forename: Joel
authors.initials: J
authors.lastname: Wood
authors.forename: Selma
authors.initials: S
authors.lastname: Maendel
authors.forename: David
authors.initials: D
authors.lastname: Gross
authors.forename: Tony
authors.initials: T
authors.lastname: Waldner
authors.forename: Joseph
authors.initials: J
authors.lastname: Eaton
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Monk
authors.forename: Vishwajit L
authors.initials: VL
authors.lastname: Nimgaonkar
mesh_terms: D002940:Circadian Rhythm / Q000502:physiology*; D005006:Ethnicity; D005260:Female; D005858:Germany / Q000208:ethnology; D006801:Humans; D008019:Life Style; D008297:Male; D010414:Pennsylvania; D012890:Sleep / Q000502:physiology*; D011795:Surveys and Questionnaires; D014851:Wakefulness / Q000502:physiology