Background: Obstructive sleep apnea (OSA) is associated with increased vagal activity, sympathetic nervous system activation, and cardiovascular complications. Excessive daytime sleepiness (EDS) in OSA patients is a predictor of cardiovascular and all-cause mortality. Heart rate variability (HRV) can be used to assess cardiac autonomic modulation, which is affected by OSA. This study aimed to evaluate the relationship between HRV and daily sleepiness in OSA patients based on the excessive sleep scale (ESS) scores.
Materials and Methods: The study included 70 patients with OSA, divided into two groups: those with EDS (ESS ≥ 11) and those without sleepiness (ESS < 11). Time and frequency domain parameters were evaluated. The results were compared and analyzed between the two groups.
Results: Patients with OSA and EDS had higher cardiovascular risk, as indicated by different HRV parameters (higher low-frequency parameter and higher time domain parameters), compared to non-sleepy OSA patients. A significant positive correlation was found between ODI and AHI with VLF, and significantly higher LF and VLF in EDS patients.
Conclusion: OSA patients with EDS had higher cardiovascular risk, as indicated by different HRV parameters, compared to non-sleepy OSA patients. A significant positive correlation was found between ODI and AHI with VLF, and significantly higher LF and VLF in EDS patients. Further studies are needed to better understand the relationship between HRV and daily sleepiness in patients with OSA.