Prevalence of positional obstructive sleep apnea in patients undergoing polysomnography and the effect of sleep stage

Determining whether sleep apnea is positional or not has important therapeutic consequences as discussed elsewhere in this book. In this chapter, we will discuss the prevalence of positional sleep apnea in patients with sleep apnea, factors that make positional sleep apnea more likely in a patient with sleep apnea, and the effect of sleep stage on positional sleep apnea. Using the standard definition for positional sleep apnea, the prevalence varies from 56 % to 71 %. Using a stricter definition where sleep apnea is only observed in the supine posture, the prevalence varies from 23 % to 27 %. Positional sleep apnea is substantially more common in patients with milder disease. Positional sleep apnea is present during both REM and NREM sleep.