Study objectives: To examine the rates of family history of insomnia in a population-based sample composed of self-defined good sleepers and individuals with insomnia and compare individuals with and without family history of insomnia on several characteristics presumably associated with insomnia.
Design: Cross-sectional comparisons of self-defined good sleepers and individuals with insomnia selected from a larger epidemiologic study using a randomly selected sample of 2001 adults of the province of Quebec in Canada.
Participants: Nine hundred fifty-three adults (60.3% women; mean age = 43.9 years) completed several postal questionnaires, including a survey of past and current history of insomnia/sleep disorders for self and first-degree relatives. Participants were classified as good sleepers, individuals with insomnia symptoms, or individuals with an insomnia syndrome.
Results: Of the total sample, 34.9% reported at least 1 first-degree relative with past or current insomnia. The mother was the most frequently afflicted first-degree relative with insomnia (19.7%). Family history rates of insomnia were not significantly different when individuals with current insomnia symptoms or syndrome were compared with self-defined good sleepers. However, significant group differences emerged when good sleepers were subdivided according to the presence or absence of past personal history of insomnia. Individuals with past or current insomnia were significantly more likely to report a family history of insomnia than were good sleepers who had never experienced insomnia in the past (39.1% vs 29.0%). Participants with a family history of insomnia endorsed higher scores on measures of insomnia severity, anxiety symptomatology, and arousal predisposition.
Conclusions: These findings provide additional evidence about the potential role of both family and personal history of insomnia as predisposing factors to insomnia. Longitudinal family studies are needed to further examine the relative contribution of genetic and environmental factors in the genesis and heritability of insomnia.