The relationships between insomnia, sleep apnoea and depression: findings from the American National Health and Nutrition Examination Survey, 2005-2008.

Objective: To determine the association between insomnia, obstructive sleep apnoea (OSA), and comorbid insomnia- OSA and depression, while controlling for relevant lifestyle and health factors, among a large population-based sample of US adults. Method: We examined a sample of 11,329 adults (≥18 years) who participated in the National Health and Nutrition Examination Survey (NHANES) during the years 2005-2008. Insomnia was classified via a combination of self-reported positive physician diagnosis and high-frequency \u27trouble falling asleep\u27, \u27waking during the night\u27, \u27waking too early\u27, and \u27feeling unrested during the day\u27. OSA was classified as a combination of a positive response to a physician-diagnosed condition, in addition to a high frequency of self-reported nocturnal \u27snoring\u27, \u27snorting/stopping breathing\u27 and \u27feeling overly sleepy during the day\u27. Comorbid insomnia-OSA was further assessed by combining a positive response to either insomnia (all), or sleep apnoea (all), as classified above. Depressive symptomology was assessed by the Patient Health Questionnaire-9 (PHQ-9), with scores of >9 used to indicate depression. Odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disorders and depression were attained from logistic regression modelling adjusted for sex, age, poverty level, smoking status and body mass index (BMI). Results: Those who reported insomnia, OSA or comorbid insomnia-OSA symptoms reported higher rates of depression (33.6%, 22.2%, 27.1%, respectively), and consistently reported poorer physical health outcomes than those who did not report sleep disorders. After adjusting for sex, age, poverty level, smoking status and BMI (kg/m2), insomnia (OR 6.57, 95% CI 3.89-11.11), OSA (OR 5.14, 95% CI 3.14-8.41) and comorbid insomnia-OSA (OR 6.67, 95% CI 4.44-10.00) were associated with an increased likelihood of reporting depression. © The Royal Australian and New Zealand College of Psychiatrists 2014.