Cardiovascular and autonomic modulation during nighttime rest under real-world conditions in miners exposed to chronic intermittent hypoxia.

Background: Chilean mine workers commuting between sea level (SL) and high altitude (HA) are repeatedly exposed to chronic intermittent hypoxia (CIH). However, cardiovascular responses during nighttime rest, particularly the combined behavior of blood pressure (BP) and heart rate variability (HRV), remain insufficiently characterized under real-world occupational field conditions. Methods: Nineteen male mine workers (35-55 years) with over 10 years of rotational work (7-on/7-off shifts) were evaluated at SL (<500 m) and HA (∼3,800 m). Participants were classified as normotensive (NT, n = 9) or hypertensive (HT, n = 10). Resting SpO Results: SpO Conclusion: CIH exposure is associated with reduced oxygen saturation, elevated BP, and decreased vagal modulation during a standardized nighttime rest period under real-world conditions. Although HRV and BP changed in parallel at the group level, their individual associations were weak, suggesting that short-term cardiac vagal modulation alone does not fully explain BP responses during this predefined rest window under hypoxic stress. These findings describe field-based autonomic-hemodynamic responses during nighttime rest in CIH-exposed male workers.