Socioeconomic status and insomnia

This investigation compared the likelihood of insomnia and insomnia-related health consequences among individuals of different socioeconomic status. A random-digit dialing procedure was used to recruit at least 50 men and 50 women in each age decade from 20 to 80+ years old. Participants completed 2 weeks of sleep diaries as well as questionnaires related to fatigue, sleepiness, and psychological distress. Socioeconomic status was measured by education status assessed at 3 different levels: individual, household, and community. Results indicated that individuals of lower individual and household education were significantly more likely to experience insomnia even after researchers accounted for ethnicity, gender, and age. Additionally, individuals with fewer years of education, particularly those who had dropped out of high school, experienced greater subjective impairment because of their insomnia.     

Primary versus secondary insomnia in older adults: subjective sleep and daytime functioning

Most psychological research on insomnia has centered on primary insomnia (PI). Secondary insomnia (SI), though more common than PI, has received little attention because of its presumed unresponsiveness to treatment. The present study recruited older adults with PI, SI, and a comparison group of older adults with no insomnia (NI). Self-report assessments of sleep revealed no significant difference between the 2 insomnia groups. Daytime functioning measures found significant differences in impairment between the 3 groups with SI having the worst daytime functioning, followed by PI, which was worse than NI. Further analyses found substantial independence between sleep and daytime functioning. Implications of these findings for the clinical management of SI are discussed.     

Quantitative criteria for insomnia

Formal diagnostic systems (DSM-IV, ICSD, and ICD-10) do not provide adequate quantitative criteria to diagnose insomnia. This may not present a serious problem in clinical settings where extensive interviews determine the need for clinical management. However, lack of standard criteria introduce disruptive variability into the insomnia research domain. The present study reviewed two decades of psychology clinical trials for insomnia to determine common practice with regard to frequency, severity, and duration criteria for insomnia. Modal patterns established frequency (> or =3 nights a week) and duration (> or =6 months) standard criteria. We then applied four versions of severity criteria to a random sample and used sensitivity-specificity analyses to identify the most valid criterion. We found that severity of sleep onset latency or wake time after sleep onset of: (a) > or =31 min; (b) occurring > or =3 nights a week; (c) for > or =6 months are the most defensible quantitative criteria for insomnia.