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

Abstract

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. 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. 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. This study suggests that AA intervention leads to more cardiac parasympathetic and less cardiac sympathetic activity, which contributes to the improvement of PI.