Sleep disorders in individuals with mental illnesses can be a symptom of the underlying condition, an independent disorder, or an indication of sleep medicine-related issues. Treatment depends on the cause and ranges from psychoeducational measures to behavioral therapy and medication, as well as mechanical therapy forms. This book summarizes the essentials of sleep medicine for all those who treat sleep-disordered individuals in the field of mental health. It explains the fundamentals of sleep and sleep disorders and illustrates the connections and interactions between sleep disorders and mental illnesses. Various methods and options for diagnosis and therapy are discussed, along with social medicine aspects and sleep disorders in consultative services.