Is parasomnia a disease?

Can be. Parasomnias are the result of sleep that has similarities to waking behaviors. An example would be sleepwalking or sleeptalking. In these examples the patient engages in behaviors that look like they are awake but their brian is sleeping. When parasomnias disrupt quality of sleep, cause problems like falling out of bed, wandering out of the home, or violent behaviors, it is time to see a doctor.