Familial incidence of insomnia.

This study evaluated the familial incidence of sleep disturbances among individuals with insomnia complaints. The sample consisted of 285 patients evaluated for insomnia at a sleep disorders clinic. All patients completed a sleep survey and underwent a semistructured clinical interview as part of their initial evaluation of insomnia. Information on the presence and nature of sleep disturbances among their family members (first- and second-degree relatives) was obtained from a sleep survey. The findings indicate that 35% of patients consulting for insomnia had a positive family history of sleep disturbances. Insomnia was the most common type of sleep disturbance identified (76%) and the mother was the most frequently afflicted family member. Reports of sleep disturbances among a family member were more prevalent when the onset of insomnia was before 40-years-old than when it was later in life. A positive family history was slightly higher when the insomnia complaint involved sleep-onset difficulties relative to sleep-maintenance or mixed insomnias. Although the present findings suggest that a positive family history of insomnia may be a potential risk factor for insomnia, it is unclear whether this reflects a genetic predisposition or a social learning phenomenon.