On the potential clinical relevance of the length of arousals from sleep in patients with obstructive sleep apnea.

STUDY

OBJECTIVES

To assess, in individuals referred for evaluation of obstructive sleep apnea, the potential clinical significance of brief versus longer arousals from sleep.

METHODS

Full-night polysomnographic tracings from 100 patients referred for evaluation of obstructive sleep apnea were analyzed to delineate the duration of each arousal event. These data were then correlated to the patient's subjective perception of sleepiness as estimated by the Epworth Sleepiness Scale (ESS).

RESULTS

A significant relationship (p < .0001, r(2) = .167) was noted between the frequency of the longer arousals (> 15 seconds) and the ESS. This relationship was significant, but distinctly weaker (p = .004, r(2) = .073), with the shorter arousals (3-15 seconds); moreover, the association with the brief arousals failed to remain significant (p = .678) after controlling for the effect of the longer arousals.

CONCLUSIONS

Individuals with obstructive sleep apnea experience frequent respiratory event associated cortical arousals, many of which are greater than 15 seconds in duration. These longer arousals, which, in this study, constituted 18.4% of all arousals and accounted for 37.5% of the total arousal time, correlate more closely with the ESS than does the frequency or time attributable to the more numerous brief arousals. This suggests that these more-prolonged arousal events may have a greater impact on the restorative aspect of sleep, or on the perception thereof.