Background Of Insomnia

Insomnia is defined as repeated difficulty with the initiation, duration, maintenance, or quality of sleep that occurs despite adequate time and opportunity for sleep that results in some form of daytime impairment. Approximately one third of adults report some difficulty falling asleep and/or staying asleep during the past 12 months, with 17% reporting this problem as a significant one. Insomnia can be acute or chronic. Acute adjustment insomnia occurs in the context of an identifiable stressor (eg, personal loss, change in interpersonal relationships, bereavement, occupational stress, job loss) that acts as a precipitating factor. It typically lasts 3 months or less, and resolves as the stressor is no longer present or as the individual adapts to the stressor. The 1-year prevalence of adjustment insomnia in adults is approximately 10-15%.

Despite inadequate sleep, many patients with insomnia do not complain of excessive daytime sleepiness, such as involuntary episodes of drowsiness in boring, monotonous, nonstimulating situations. However, they do complain of feeling tired and fatigued with poor concentration. This may be related to a physiological state of hyperarousal (seePathophysiology). In fact, despite not getting adequate sleep, patients with insomnia oftentimes have difficulty falling asleep even during daytime naps.

Chronic insomnia also has numerous health consequences. For example, patients with chronic insomnia report reduced quality of life comparable to other conditions such as diabetes, arthritis, and heart disease. Quality of life improves with treatment but still does not reach the level seen in the general population. In addition, chronic insomnia is associated with impaired occupational and social performance and an elevated absenteeism rate that is 10-fold greater than controls. Furthermore, insomnia is associated with higher healthcare use, including a 2-fold increase in hospitalizations and office visits.

Insomnia can also be a risk factor for depression and a symptom of a number of medical, psychiatric, and sleep disorders. In fact, insomnia appears to be predictive of a number of disorders, including depression, anxiety, alcohol dependence, drug dependence, and suicide. The annual cost of insomnia is not inconsequential with the estimated annual costs for insomnia at $12 billion dollars for healthcare and $2 billion dollars for sleep promoting agents.

In 2005, the National Institutes of Health held a State of the Science Conference on the Manifestations of Chronic Insomnia in Adults. This conference focused on the definition, classification, etiology, prevalence, risk factors, consequences, comorbidities, public health consequences and the available treatments and evidence for their efficacy. A summary of this conference can be obtained at the NIH Consensus Development Program home page. Prior to this conference, most cases of chronic insomnia were widely believed to be secondary to another medical or psychiatric condition and effective treatment of the primary condition was believed to effectively address secondary insomnia. However, at this 2005 conference, based on the review of the literature and the panel experts, the following was concluded:

Most causes of insomnia are co-morbid with other conditions. Historically, this has been termed secondary insomnia. However, the limited understanding of the mechanistic pathways precludes drawing firm conclusions about the nature of these associations or directions of causality. Furthermore, there is concern that the term secondary insomnia may promote under treatment. Therefore, we propose the term comorbid insomnia.

This is an important point since insomnia is often only a secondary symptom that will resolve once the primary cause, whether it be medical or psychiatric, is treated. Consequently, this results in the underrecognition and undertreatment of insomnia. Furthermore, oftentimes if sleep difficulties are not the presenting complaint, there is too little time to address them at an office visit. There is also very little training in medical school on sleep disorders and their impact on patient overall health and quality of life. In fact, most providers rate their knowledge of sleep medicine as only fair. Finally, many providers are not aware of the safety issues, efficacy of cognitive behavioral and pharmacologic therapies, or when to refer a patient to a sleep medicine specialist.

Insomnia often persists despite treatment of the underlying medical or psychiatric condition and the persistence of insomnia can increase the risk of relapse of the primary condition in certain cases. In this regard, the clinician needs to understand that insomnia is a condition in its own right that requires prompt recognition and treatment to prevent morbidity and improve quality of life for their patients.