Understanding the Sleep-Wake Cycle: Sleep, Insomnia, and the Orexin System

Abstract

Insomnia is a common, chronic, and pervasive sleep disorder in which people regularly have difficulty falling asleep and/or staying asleep despite an adequate opportunity to sleep. According to the International Classification of Sleep Disorders, insomnia is defined as not getting enough sleep or not feeling rested after sleep and is associated with daytime impairments such as diminished quality of life, fatigue, restlessness, irritability, anxiety, or tiredness. People who have insomnia often experience physical and emotional problems, an increased occurrence of accidents and comorbid psychiatric disorders, a loss of work productivity due to absenteeism, and difficulty performing work duties.

Although insomnia is a prevalent and serious problem, it is underdiagnosed and undertreated. Recent research into the sleep-wake cycle and how disruptions to that cycle can cause sleep disorders may provide some promise for new insomnia treatments. Andrew D. Krystal, MD, MS, gathered a panel of experts in the area of the sleep-wake cycle and insomnia to review recent research and advances in understanding, current treatments for insomnia, and how those new advances might be translated into new, more effective treatments.