Sleep problems are ubiquitous in the modern world, significantly impacting on quality of life, mental health, and performance at work and at home. More significantly, sleep problems accompany almost every mental health condition and are a significant driver in the development and maintenance of poor mental health. This book describes the current state of knowledge on the science of sleep, covering the various forms of insomnia and parasomnia that abound, before discussing the variety of assessment and treatment options available to the healthcare practitioner. Further discussion of psychological and behavioural interventions is made with particular reference to a new, second-generation Cognitive Behavioural Therapy for insomnia, how this is an effective treatment modality, and how it can be applied with clients presenting with more complex physical and mental health conditions. The final chapter presents the range of theories as to the purpose and function of dreams and dreaming, and how 'dream-work' has been applied in the therapeutic setting.