ABSTRACT
In a general sense, insomnia suggests inadequate sleep quality or quantity when one has an adequate opportunity to sleep. When defined as a sleep disorder, insomnia is characterized by difficulty falling asleep or remaining asleep, which may represent problems with sleep maintenance or early morning awakening despite attempts to be sleeping. Sleep disorder nosologies also may include a complaint of nonrefreshing sleep as an insomnia complaint. For a diagnosis of an insomnia disorder to be made, daytime consequences or functional impairment also should be present. These may include fatigue, inability to concentrate, or irritability. Insomnia may be characterized as primary or comorbid (1). Primary insomnia occurs independently while comorbid insomnia presumably is associated with a sleep disturbance related to another disorder. Insomnia affects approximately 30% of the general population at least occasionally and is a severe or chronic problem for about 10% of the population. Patients with co-occurring conditions have significantly increased risk for insomnia (2). People suffering with insomnia have increased healthcare costs and utilize health resources to a greater extent. They also have worse scores on quality-of-life measures. Persistent insomnia has been identified as a risk factor for the development or exacerbation of certain psychiatric and medical conditions. Overall, insomnia represents a significant socioeconomic burden both for individuals and for society. This chapter will provide an overview of current perspectives on the causes, consequences, and associations of insomnia.
ETIOLOGY, PATHOPHYSIOLOGY, AND PATHOGENESIS
