Sleep disturbances are commonly associated with anxiety disorders, particularly generalized anxiety disorder, panic disorder, and posttraumatic stress disorder. Core features of panic disorder and posttraumatic stress disorder occur in relation to sleep (sleep panic attacks, re-experiencing nightmares). These sleep episodes can usually be distinguished from primary sleep disorders on clinical grounds. Such conditions may coexist, however, and anxiety symptoms seem to benefit from treatment of sleep respiratory conditions. Established treatments for anxiety disorders and insomnia have many overlapping components; however, optimal sequencing and integration of the approaches is presently inadequately investigated.