Co-occurrence of Insomnia and Anxiety Disorders: A Review of the Literature

Insomnia and anxiety disorders are highly prevalent and are associated with significant impairment and disability. There is evidence that insomnia and anxiety disorders commonly co-occur, in addition to both being highly comorbid with major depressive disorder. Thus, it is important for health care providers to be familiar with the literature in this area. Therefore, the purpose of this review was to examine the empirical literature on the co-occurrence of insomnia and anxiety disorders, as well as discuss the clinical and research implications of the findings. Studies were identified through PubMed and PsycINFO searches (1975-2007) and a bibliographic review of published articles. The results from this literature review suggest that certain anxiety disorders, such as panic disorder and generalized anxiety disorder, are clearly associated with symptoms of insomnia (eg, delayed sleep onset, restless sleep). Although there are some discrepancies in the literature, the findings suggest that individuals with posttraumatic stress disorder also experience significant sleep problems (eg, middle-of-the-night insomnia, poor sleep quality, nightmares), and the presence of such problems during the early posttrauma period predicts later development of the disorder. Few empirical studies examine sleep in other anxiety disorders, and the majority of studies on insomnia and anxiety disorders in general have not examined the effects of comorbid major depressive disorder, indicating a need for additional research. Overall, the findings highlight the importance of screening for and treating anxiety symptoms when a patient presents with symptoms of insomnia and vice versa. Clearly, treatment development work on interventions that address co-occurring insomnia and anxiety disorders is greatly needed.