Sleep disturbances are hallmark symptoms of posttraumatic stress disorder (PTSD). Where the subjective experience of nightmares and insomnia in PTSD patients is very real indeed and demands treatment, objective research findings on disordered sleep architecture in PTSD are inconclusive and inconsistent. After reviewing the literature an insufficient number of controlled studies are published to formulate evidence-based guidelines. Several studies have methodological limitations, such as small group sizes and heterogenic samples. Large randomized controlled trials (RCTs) need to be conducted in order to further develop adequate therapeutic interventions. Objective parameters for insomnia and nightmares need to be identified for understanding underlying mechanisms of disturbed sleep in PTSD, and for evaluating therapy.