Insomnia disorders

**Definition:** Insomnia disorders are characterised by the complaint of persistent difficulty with sleep initiation, duration, consolidation, or quality that occurs despite adequate opportunity and circumstances for sleep, and results in some form of daytime impairment. Daytime symptoms typically include fatigue, depressed mood or irritability, general malaise, and cognitive impairment. Individuals who report sleep related symptoms in the absence of daytime impairment are not regarded as having an insomnia disorder.