Introduction: Sleep-disordered breathing across the life span: exploring a human disorder using animal models

Sleep-disordered breathing (SDB) is a constellation of breathing disorders that occur during sleep. Obstructive sleep apnea (OSA), the most common form, is characterized by complete or partial airway obstruction, hypoventilation, and central apneas, all of which lead to recurrent episodes of hypoxia, hypercapnia, sleep fragmentation, and elevated sympathetic tone. OSA occurs throughout the life span and is associated with significant cognitive, metabolic, and cardiovascular consequences that impair the quality of life. Building on observations that the upper airway collapses during sleep, obesity increases the risk of upper airway obstruction, and this obstruction leads to periods of hypoxia and reoxygenation that cause oxidative stress, researchers used large and small animal models to study the genetic predeterminants of OSA, the neuromechanical control of the upper airway during development and aging, and the metabolic consequences of oxidative stress. From the early canine models of experimentally induced upper airway obstruction to the current rodent models of intermittent hypoxia, the information now available has significantly improved scientists' understanding of the pathogenesis of OSA and its consequences, leading to better care for individuals with sleep-disordered breathing.