Objective: Insomnia can be broadly defined as difficulty initiating or maintaining sleep, or sleep that is not refreshing or of poor quality with negative effect on daytime function. Insomnia can be a primary condition or comorbid to an underlying disorder. Subjective measures of insomnia used in population studies, usually based on complaints of unsatisfactory sleep, put the prevalence at about 10%. Insomnia is more common in the elderly and in women, and is often associated with medical and psychiatric disorders. This review examines the measures used to assess quality of sleep (QOS) and daytime functioning and the impact of insomnia on society using these measures.
Methods: Literature searches were performed to identify all studies of insomnia (primary and comorbid) in adults (aged 18-64 years) and the elderly (aged ≥ 65 years) with baseline and/or outcomes relating to QOS or daytime functioning. The impact of poor QOS on quality of life (QOL), psychomotor and cognitive skills, health care resource utilization, and other societal effects was examined.
Results: Although definitions and measurement scales used to assess sleep quality vary widely, it is clear that the societal consequences of insomnia are substantial and include impaired QOL and increased health care utilization. The impact of poor QOS and impaired daytime functioning common in insomnia can lead to indirect effects such as lower work productivity, increased sick leave, and a higher rate of motor vehicle crashes.
Conclusions: Insomnia is associated with substantial direct and indirect costs to society. It is almost impossible to separate the costs associated with primary and comorbid insomnia. More studies are required which control for the severity of any primary disorder to accurately evaluate the costs of comorbid insomnia. Development of standardized diagnostic and assessment scales will enable more accurate quantification of the true societal burden of insomnia and will contribute to greater understanding of this disorder.
Keywords: health care resource utilization; insomnia; quality of life; quality of sleep; societal cost.