The relationship of subjective sleep quality and cardiac autonomic nervous system in postmenopausal women with insomnia under auricular acupressure

Objective: The aim of this study is to examine the relationship between the changes in self-reported sleep symptoms and cardiac sympathovagal activity among women with postmenopausal insomnia (PI) who received auricular acupressure (AA) therapy. Methods: A pretest/posttest study design was conducted at Taipei Veterans General Hospital, Taiwan, from August 2008 to July 2009. Forty-five women (mean +/- SD age, 56.2 +/- 5.4 years) with PI (4.9 +/- 3.5 years of insomnia) received an AA therapy course on five auricular points every night before going to sleep for 4 weeks. Heart rate variability (HRV), the Chinese version of the Pittsburgh Sleep Quality Index, and the Menopause Rating Scale were measured before and after AA treatment. Results: The total sleep duration and sleep efficiency were increased, and the sleep latency was shortened significantly (P < 0.01) after AA therapy. The total Menopause Rating Scale and somatovegetative subscale scores were reduced significantly (P < 0.05) after the intervention. A greater percentage change in Pittsburgh Sleep Quality Index was moderately correlated with both a lower percentage change in high-frequency power of HRV (r = -0.660, P < 0.001) and a greater percentage change in normalized low-frequency power (nLF) of HRV (r = 0.599, P < 0.001). An elevation of high-frequency power and a reduction of nLF of HRV were observed in the responder group, whereas a raise in nLF of HRV was noted in the nonresponder group. Conclusions: This study suggests that AA intervention leads to more cardiac parasympathetic and less cardiac sympathetic activity, which contributes to the improvement of PI.