Chapter 23 - Pharmacology of anxiety and sleep disorders

Abstract

Anxiety disorders are distressing, unpleasant, and the most common class of psychiatric disorders. The affected individual is nervous and uneasy, and may experience physical changes and behaviors similar to those related to fear. Anxiety triggers the sympathetic nervous system and symptoms of the fight-or-flight response may occur. The most common anxiety disorders include generalized anxiety disorder, social anxiety disorder, panic disorder, and obsessive-compulsive disorder. Post-traumatic stress disorder is also related since patients often report anxiety, even when there is no present danger. Brain areas involved in anxiety include the limbic system, reticular activating system, and locus ceruleus of the brainstem. Sleep disorders involve problems falling or staying asleep, falling asleep at the wrong times, excessive sleep, and abnormal sleep behaviors. Insomnia is a component of many sleep disorders. Circadian rhythm disorders are related to lack of balance between internal sleep-wake rhythms and the cycle of light to darkness. Anxiety and sleep disorders were initially treated with barbiturates and benzodiazepines, but as the barbiturates caused many adverse effects, addiction, and dependence, the benzodiazepines became preferred. They have two classifications: sedative-hypnotics and anxiolytics. Miscellaneous drugs (nonbenzodiazepines) followed. Newer drugs for anxiety and sleep disorders include the atypical drugs–melatonin agonists and orexin antagonists.