SLEEP PROPENSITY AND SLEEP-RELATED BREATH ING DISORDERS

Daytime sleepiness is one of the major symptoms of obstructive sleep a pnea. However, its definition raises problems, since it,nay be based o n either subjective feeling (evaluated by means of questionnaires or a nalog visual scales), physiological drive or need (inferred by a sleep latency) or on the concept of sleep propensity defined as the probabi lity of falling asleep (measured by the occurrence of sleep in various circumstances of daily life). Data from the literature suggest that s leep fragmentation and hypoxemia, both related to sleep apneas, cause daytime sleepiness. Our own data show that sleep propensity in a group of 44 patients with obstructive sleep apnea war correlated with the i ncrease in esophageal pressure swings during obstructive apneas. This result suggests that the increased respiratory effort against occluded upper airways also contributes to daytime sleepiness in patients with obstructive sleep apnea.