What is sleep-disordered breathing (SDB)?

Updated: Feb 13, 2020
  • Author: Vittorio Rinaldi, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Upper-airway obstruction occurring during sleep—that is, sleep-disordered breathing (SDB)—was first demonstrated in the 1960s. SDB represents a group of physiopathologic conditions that are characterized by an abnormal respiratory pattern during sleep that can be isolated or can coexist with other respiratory, nervous, cardiovascular, or endocrine diseases. SDB is now known to be widely prevalent in the general population, and it is responsible for or contributes to numerous problems, ranging from fragmented sleep patterns to hypertension to traffic accidents. [1, 2]

SDB includes obstructive sleep apnea (OSA), which consists of breathing cessations of at least 10 seconds occurring in the presence of inspiratory efforts during sleep. Central sleep apnea (CSA) consists of similar apneas, but these instead take place in the absence of inspiratory efforts. [3, 4, 5, 6, 7]

OSA syndrome (OSAS) is a potentially disabling condition characterized by excessive daytime sleepiness, [8]  disruptive snoring, repeated episodes of upper-airway obstruction during sleep, and nocturnal hypoxemia. It is defined by an apnea-hypopnea index (the total number of episodes of apnea and hypopnea per hour of sleep), or respiratory disturbance index (RDI), of 5 or higher in association with excessive daytime somnolence.

Risk factors for sleep apnea include obesity, increased neck circumference, craniofacial abnormalities, hypothyroidism, and acromegaly. Daytime consequences include not only excessive sleepiness but also impaired cognitive performance and disturbed moods with a reduced quality of life. Excessive daytime sleepiness is reported to be associated with a higher risk of motor vehicle accidents and work place injuries or poor work performance .

In general, everyone with SDB snores, but not everyone who snores has SDB. Snoring in the absence of SDB is termed primary or simple snoring. However, some evidence indicates that snoring is one end of a clinical continuum, with severe OSA at the opposite end. Some health problems may be associated even with primary snoring. The relation between snoring sounds and severity of OSAS has been widely investigated. [9]

Upper-airway resistance syndrome (UARS) is characterized by snoring with increased resistance in the upper airway, resulting in arousals during sleep. This can disturb sleep architecture to the point of causing daytime somnolence. No distinct diagnostic criteria exist for this entity. Patients with UARS can be treated with continuous positive airway pressure (CPAP)—specifically, nasal CPAP (n-CPAP). [10, 11]

Treatment involves elimination of contributing factors and provision of n-CPAP. n-CPAP is effective in improving sleep quality and reducing daytime sleepiness. Long-term treatment with n-CPAP reduces both mortality and the acute blood pressure elevation that occurs with SDB. [12]  Over time, a trend develops toward baseline blood pressure reduction in hypertensive patients with SDB. Medical and surgical interventions may also be indicated.

Go to Obstructive Sleep ApneaChildhood Sleep ApneaCentral Sleep Apnea SyndromesObstructive Sleep Apnea and Home Sleep MonitoringSurgical Approach to Snoring and Sleep ApneaOral Appliances in Snoring and Obstructive Sleep Apnea, and Upper Airway Evaluation in Snoring and Obstructive Sleep Apnea for more information of these topics.

For patient education information, see the Sleep Disorders Center, as well as Snoring and Narcolepsy.

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