Insomnia is associated with a number of medical and psychiatric disorders, including chronic pain and clinical depression. Until recently, it was assumed that effective treatment of the underlying medical condition would also correct the sleep disturbance. However, some evidence indicates that treatment of secondary or comorbid insomnia should be considered separately from, and perhaps in addition to, optimizing treatment of the primary condition.
This article reviews the extant literature to examine the impact of secondary and comorbid insomnia on the patient, and on healthcare economics, in the primary care setting, and discusses current diagnostic and treatment approaches. A MEDLINE search was performed for literature published from 1980 to 2005, and retrieved randomized, controlled clinical trials and key review articles for the conditions most often accompanied by secondary insomnia: depression, chronic pain, and menopause/perimenopause. The search terms included those for commonly used pharmacologic treatments and behavioral therapy.
Due to the paucity of clinical trial data in secondary insomnia patients, physicians have had to rely on evidence derived from primary insomnia trials. These data indicate that hypnotic medications are effective in treating sleep onset insomnia. However, few of these agents are effective against the most commonly occurring insomnia symptom - poor sleep maintenance - and many are associated with problematic residual sedation. Nevertheless, the cost of not treating these insomnia symptoms is often greater than the treatment inadequacies. Physicians should thus consider treating what they perceive as secondary insomnia with one of the available forms of therapy.
Patients experiencing sleep problems associated with a potential medical or psychiatric primary condition would likely benefit from increased physician awareness of secondary insomnia and the subsequent increased attention to diagnosing and treating this prevalent condition. Recommendations for managing secondary or comorbid insomnia in the primary care setting are discussed.