(HealthDay News) – Women experiencing hot flashes have a significant reduction in heart rate variability during the hot flash, suggesting a role for the autonomic nervous system, according to a study published in the April issue of Menopause.

Rebecca C. Thurston, PhD, from the University of Pittsburgh, and colleagues estimated heart rate variability, an index of cardiac vagal control, using the band-limited variance method. Physiologic and reported hot flashes and heart rate variability were monitored over a 24-hour period during the daily lives of 21 perimenopausal and postmenopausal women, aged 40–60 years, reporting daily hot flashes.

The researchers observed a significant decrease in heart rate variability during hot flashes compared to periods before and after. They note that this had previously been observed in the laboratory. The findings were independent of respiratory rate.

“Significant decreases in cardiac vagal control occurred during hot flashes assessed during women’s daily lives,” Thurston and colleagues conclude, “These findings extend our work in the laboratory to the ambulatory setting, further shedding light on the physiology of hot flashes and underscoring a potential role of parasympathetic function in hot flashes.”

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