The disorders in the subgroup are characterized by disordered respiration during sleep characterized by abnormal pauses in breathing or instances of abnormally low breathing during sleep. Complete or near complete cessation in breathing is called an apnea, and diminished respiratory effort with oxygen desaturation or an arousal is called a hypopnea. These can last from a few seconds to minutes, and occur at least 5 times or more an hour in adults. Patients typically present with excessive daytime sleepiness (EDS) and impaired alertness. Patients with central sleep apnea may present with sleep maintenance insomnia.
Obstructive sleep apnea (OSA) is the most common category of sleep disordered breathing. The obstructive sleep apnea syndromes include those in which there is an obstruction in the airway resulting in continued breathing effort but inadequate ventilation. Snoring is prominent secondary to vibration of the posterior airway. Typically the obstructive sleep apnea is worse in the supine position (on the back) and also during REM sleep. Patients with a body mass index of greater than 30, neck size greater than 16 inches in women and 17 inches in men enlarged tonsils, large tongue, and micrognathia may be at higher risk. Besides EDS, patient’s may also have an increased risk for hypertension, cardiovascular disease, sexual dysfunction, memory dysfunction, and mood disorders.
Central sleep apnea syndromes include those in which respiratory effort is diminished or absent and intermittent or cyclic fashion secondary to central nervous system or cardiac dysfunction. It is believed that this is secondary to the central nervous system not sending proper signals to the respiratory centers to maintain breathing during sleep. Less than 5 percent of sleep apnea is secondary to central sleep apnea.