Sleep Disorders
Sleep Physiology
Sleep cycle: sequence of stages 1, 2, 3, 4, followed by the reverse (4, 3, 2), followed by rapid eye movement (REM) period. Typical cycle duration 80 to 120 minutes. Normal sleep pattern: 3 to 5 repetitions of sleep cycle.
Excessive daytime sleepiness may result from insufficient quantity of sleep or poor sleep quality from sleep disorder.
Diagnostic Procedures
Clinical polysomnography: simultaneous recording of sleep and physiologic variables (EEG, electrooculogram, EMG, ECG, respiratory effort, oxygen saturation).
Multiple sleep latency test: useful for evaluation of daytime sleepiness (time taken to fall asleep, normal >10 mins); also to detect sleep-onset REM (narcolepsy, REM sleep rebound).
Selected Disorders of Sleep
Disorders with Insomnia
Transient insomnia: duration <3 weeks; usually situational.
Psychophysiologic insomnia: multiple contributing factors: initiating stressor, maladaptive habits perpetuate problem. Treatment: behavioral therapy, sleep hygiene (Table 145.1).
Persistent, chronic insomnia: many underlying causes, including medical and psychiatric diorders. Treatment directed at cause.
Insomnia may be a complaint in patients with sleep disruption due to obstructive sleep apnea, narcolepsy, restless legs syndrome (see below).
Sleep-Related Respiratory Disorders
Obstructive Sleep Apnea (OSA) Syndrome
Repeated apneas due to collapse, obstruction of upper airway. Predominantly ages 30 to 50. M:F ratio 2.5:1. Risk factors:
habitual snoring, obesity, upper airway abnormalities. In children, often associated with adenotonsillar hypertrophy.
habitual snoring, obesity, upper airway abnormalities. In children, often associated with adenotonsillar hypertrophy.
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