Insomnia is a disorder characterized by chronic sleep disturbance associated with daytime disability or distress, such as memory impairment and fatigue, that occurs despite adequate opportunity for sleep. Insomnia may present as difficulty falling/staying asleep or as sleep that is nonrestorative. Studies show a strong correlation between insomnia and impaired quality of life. Pain conditions and depression are commonly associated with insomnia, either as secondary or comorbid conditions. In addition, a greater incidence of anxiety, alcohol and drug dependence, and cardiovascular disease is found in people with insomnia. Data indicate insomnia results from over-engaged arousal systems. Insomnia patients experience increased metabolic rate, body temperature, and heart rate, and elevated levels of norepinephrine and catecholamines. Pharmacologic options for the treatment of insomnia include benzodiazepine hypnotics, a selective melatonin receptor agonist, and sedating antidepressants. However, insomnia may be best treated with cognitive-behavioral therapy and instruction in good sleep hygiene, either alone or in concert with pharmacologic agents. Studies on the effects of insomnia treatment use variable methodologies or do not publish negative results, and there are currently no studies of treatment focusing on morbidity. Further research is necessary to better understand the effects of insomnia therapies on medical and psychiatric disorders.

In this Clinical Information Supplement, Thomas Roth, PhD, describes the nature of insomnia and its pathophysiology. Next, Andrew D. Krystal, MD, MS, reviews morbidities associated with insomnia. Finally, Joseph A. Lieberman III, MD, MPH, provides an overview of therapeutics utilized in patients with insomnia, including behavioral therapies and pharmacologic options.