Trauma-induced insomnia is a symptom of posttraumatic stress disorder (PTSD), and is reported to be particularly distressing and often persists even after remission of the core symptoms of PTSD. Recently, it has been suggested that fear of sleep plays an important role in the development and maintenance of trauma-induced insomnia. The aim of this review is to propose a conceptual model of fear of sleep as a maintaining factor of trauma-induced insomnia. After a brief overview of the role of sleep in PTSD, the concept of fear of sleep is introduced. Theoretical considerations and empirical findings on the role of fear of sleep for trauma-induced insomnia in the context of PTSD are summarized and integrated. Specifically, links between PTSD symptoms and fear of sleep are presented, as well as possible consequences of fear of sleep leading to trauma-induced insomnia. Finally, we highlight methodological issues, identify areas for future research, and discuss potential clinical implications.