Sleep bruxism as a potential modifier of autonomic function and heart rate variability in patients with obstructive...

Obstructive sleep apnea (OSA) and sleep bruxism (SB) are prevalent conditions with frequent co-occurrence. The main objective of this study is to assess whether coexisting SB affects autonomic function in OSA subjects using heart rate variability (HRV).

A total of 146 adult subjects (83 males, 63 females) underwent overnight video-polysomnography and 24-h electrocardiography (ECG) Holter monitoring. Arrhythmias and HRV were independently assessed. All participants were diagnosed with OSA; among them, 106 also exhibited SB.

In 24-h Holter recordings, the OSA with SB group demonstrated significantly reduced Standard Deviation of NN intervals (SDNN) index (50.40 ± 18.59 vs. 51.28 ± 44.00; p = 0.03), and an increase in very low frequency (VLF) power (4957.08 ± 9984.92 vs. 2940.14 ± 4061.38; p = 0.04) when compared with the non-SB group. Daytime HRV analyses revealed a similar pattern, with significantly lower SDNN index (47.62 ± 17.48 vs. 56.07 ± 65.55; p = 0.04) and higher VLF power (864.76 ± 882.80 vs. 690.04 ± 1036.31; p = 0.03) in the OSA with SB group. Sex-specific analyses reveal that in males with SB, the HRV index and LF/HF ratio are significantly lower compared with females with SB (36.71 ± 9.74 vs. 32.99 ± 12.18; p = 0.01 and 2.51 ± 1.36 vs. 1.97 ± 1.14; p = 0.045). Additionally, normalized high-frequency power (HFnu) was also lower in males compared with females (31.48 ± 12.29 vs. 36.47 ± 12.66; p = 0.03).

The presence of SB affected HRV parameters in OSA subjects, indicating sympatho-vagal imbalance in this group. Women with OSA may be more susceptible to the adverse effects of SB. No association was observed between SB coexisting with OSA and arrhythmias.