The effect of sleep position on the diagnosis of obstructive sleep apnea: a word of caution.

Sleeping in the supine position exacerbates obstructive sleep apnea. Patients sleeping off their backs during a polysomnographic study might have a normal study in spite of having a history of severe obstructive sleep apnea. This might be shown by repeating the study with the patients spending most of the study time sleeping on their backs. We report three patients illustrating this point and discuss the importance of monitoring sleep position while performing polysomnography. The effect of position in interpreting different therapeutic modes for obstructive sleep apnea should be considered.