Chapter 22 - Sleep–wake disorders

Abstract

Sleep–wake disorders involve difficulty falling or staying asleep, falling asleep at the wrong times, excessive sleep, and abnormal sleep behaviors. The two major states of the sleep cycle are rapid eye movement and non-rapid eye movement sleep. The natural 24-hour circadian rhythm is based on alternating cycles of sleep and wakefulness. Insomnia is difficulty falling or staying asleep, awakening too early, or feeling unrefreshed after sleep. It may be induced by use of caffeine or other stimulant drugs, nighttime exercise, excitement, and an irregular sleep–wake cycle. Obstructive sleep apnea syndrome involves episodes of partial or complete upper airway closure while asleep. This leads to breathing cessation for 10 or more seconds. It usually involves loud snoring and is often concurrent with obesity. Restless legs syndrome involves abnormal leg motions while asleep and usually worsens over time without treatment. Circadian rhythm disorders are related to a lack of synchronization between sleep–wake rhythms and the cycle of light to darkness. Sleep–wake disturbances are symptoms of physical or mental abnormalities. Sleep problems can result in depression, and the reverse is also true. Sleep–wake disturbances can cause anxiety or worsen an anxiety disorder. Insufficient sleep during pregnancy may cause preeclampsia, longer labors, a more common need for cesarean delivery, hypertension, inflammation, and proteinuria. In children, sleep disorders often affect school performance and behavior.