Purpose: To determine the effect of sleep positions and sleep stages on the apnea-hypopnea index (AHI) with oxygen desaturation (OD) vs. without OD in obstructive sleep apnea (OSA) patients.

Materials and methods: A retrospective analysis was performed on anthropomorphic and nocturnal

polysomnographic (PSG) data of a group of 253 OSA patients (AHI ≥ 5) who had used both the supine position (SP) and lateral position (LP) between December 2003 and October 2006.

Results: The SP had the strongest influence on the AHI at p < 0.0001. The rapid eye movement sleep

(REMs) has influence on the AHI at p = 0.0283. The effect of the SP on AHI in patients with more body mass index (BMI) and neck circumference (NC) had lesser at p = 0.002 when categorized to nonpositional patient (NPP) and positional patient (PP). The patients with more severe apneic events had more oxygen desaturation index (ODI) than those with milder ones at p < 0.001. The patients with higher BMI had more severe apneic events than those with lesser BMI at p < 0.05.

Conclusion: The SP and REMs had effect on AHI but they had not effect on OD. There was no relationship between the sleep stages or the sleep positions and AHI with OD. The BMI appeared to be the predictor for the severity of apneic events.