The effects of sleep posture and sleep stage on apnea frequency.

The Apnea Plus Hypopnea Index (A + HI) of 60 male positional sleep apneics was analyzed by sleep stage to determine if positional differences are limited to NREM sleep. Differences in apnea severity by sleep position were found to persist in REM sleep and to be of equal extent to those differences found in NREM sleep, despite the fact that there is also a significant increase in the frequency of apneic events associated with REM sleep. The positional effect persists in REM sleep, making treatments to control sleep posture a viable option.