Prevalence of causes of insomnia in primary care: a cross-sectional study

As a result of a research interest in primary insomnia, the prevalence of other causes of insomnia in primary care must be ascertained. No source was found in the literature. It is also essential to know the epidemiology of the common causes of a condition to make an accurate diagnosis in primary care.

To determine the prevalence of causes of insomnia in primary care, as part of a method of identifying patients with primary insomnia.

Cross-sectional study in three general practices in Auckland, New Zealand.

Consecutive patients from the waiting room were asked to complete a nine-page questionnaire on possible causes of insomnia.

In total, 1517 patients were approached and 955 completed the nine-page questionnaire (63%). Of the 41% (388) who reported difficulty with sleeping, primary insomnia occurred in 12% (45) of the population (95% confidence interval = 9% to 15%); 50% (195) had depression, 48% (185) had anxiety and 43% (165) had general (physical) health problems. Obstructive sleep apnoea occurred in 9% (34) and delayed sleep phase disorder in 2% (7). Only primary insomnia and delayed sleep phase disorder are mutually exclusive; the others can co-exist.

This is the first description of the prevalence of causes of insomnia in primary care. It is hoped that the focus on primary insomnia will result in more behavioural treatments and lower the use of hypnotics in primary care; it should also assist in the appropriate detection and treatment of other causes of insomnia in primary care.