Insomnia: Pathophysiology, clinical phenotypes, and treatment options

Insomnia is a prevalent health complaint that may present as a primary disorder or as a comorbid condition to a medical or psychiatric disorder, characterized by a spectrum of symptoms reflecting dissatisfaction with the quality, duration, or continuity of sleep. These complaints may involve problems with falling asleep initially at bedtime, waking up in the middle of the night and having difficulty going back to sleep, non-restorative or unrefreshing sleep. Diagnosis also requires a report of daytime fatigue, cognitive impairments, and mood disturbances. Pathophysiology of insomnia includes both biological and psychological factors. Polysomnography (PSG) remains the gold standard for measuring sleep, and especially insomnia. Besides conventional PSG parameters, additional information can be provided by the investigation of sleep microstructure. Treatment options are based both on pharmacological and nonpharmacological approaches