The association between obstructive sleep apnea during REM sleep and autonomic dysfunction as measured by heart rate variability.

PURPOSE: To determine the effect of obstructive sleep apnea (OSA) during rapid eye movement (REM) sleep on autonomic dysfunction using heart rate variability (HRV) analysis.

METHODS: The medical records of adults who underwent nocturnal polysomnography at the Sleep and Chronobiology Center at Seoul National University Hospital were retrospectively reviewed. HRV parameters (mean RR interval, the standard deviation of all normal RR intervals [SDNN], square root of the mean squared differences of adjacent RR intervals [RMSSD], normalized low frequency [LF], normalized high frequency [HF], and the ratio of LF to HF [LF/HF]) were measured in 5-min electrocardiogram recordings obtained during W, N2, and R sleep stages. Comparisons were made among the control (apnea-hypopnea index (AHI < 15 and AHI during REM sleep (AHIREM ) < 15, n = 27), REM-associated OSA (AHI < 15 and AHIREM  ≥ 15, n = 27), and OSA (AHI ≥ 15, n = 27) groups. The groups were matched for age, sex, and body mass index.

RESULTS: No significant differences were observed between the control and the REM-associated OSA groups for any of the HRV parameters. In contrast, compared with controls, the OSA group showed significantly lower normalized HF (p = 0.031) and higher LF/HF (p = 0.018) in stage W and a significantly shorter mean RR interval (p = 0.046) and lower RMSSD (p = 0.034) in stage N2.

CONCLUSIONS: Our findings suggest that OSA during REM sleep is not a major contributor to autonomic dysfunction.