**Abstract**

Obstructive sleep apnea (OSA) is a frequent sleep disorder characterized by repetitive interruption of ventilation caused by partial or complete collapse of the upper airway during sleep. OSA is highly prevalent in the world and it has been associated with cardiovascular disease and cognitive impairment in children and adults. The cognitive impairment in individuals with OSA includes deficiencies in attention and constructional abilities, delayed long-term visual and verbal memory, and executive functions. Although, the pathogenesis of cognitive impairment in patients with OSA is complex and remains incompletely understood, several mechanisms, such as hypoxia, inflammation and sleep fragmentation have been proposed. The aim of this chapter is to describe some findings reported in the literature to explain the association between OSA and cognitive impairment.

**Keywords:** obstructive sleep apnea, cognitive impairment, hypoxia, sleep fragmentation
