RESUMO
Objectives: Although many studies have shown that acupuncture can improve sleep quality, there is no clear evidence by objective physiological measures. The authors investigated the effects of acupuncture on the autonomic indices of heart rate variability (HRV) during sleep. Design: The authors applied true acupuncture and sham-site stimulations in 10 healthy adult males (mean ± standard deviation age, 40 ± 9 years) and compared autonomic nerve indices of HRV during each sleep stage in a crossover design. The sleep stages were estimated by the combined analysis of an HRV maker of non-rapid eye movement (REM) sleep (HRV sleep index [Hsi]) and actigraphic body movement. Results: Heart rate was lower (true vs. sham acupuncture, mean ± standard error of the mean, 60.9 ± 1.8 vs. 61.7 ± 1.7 bpm, p < 0.0001) and the power of low-frequency and high-frequency components of HRV was higher (35.6 ± 2.0 vs. 34.7 ± 2.0 msec, p = 0.04 and 26.7 ± 3.2 vs. 25.8 ± 3.2 msec, p < 0.0001, respectively) after the true acupuncture compared with the sham-site stimulation throughout sleep. During non-REM sleep, heart rate was lower (59.6 ± 1.8 vs. 60.1 ± 1.8 bpm, p = 0.0004) and the power of low-frequency and high-frequency components were higher (27.7 ± 1.8 vs. 26.1 ± 1.8 msec p = 0.0004 and 28.4 ± 3.5 vs. 27.7 ± 3.5 msec, p = 0.004) after the true acupuncture than the sham-site stimulation. Whereas during REM sleep, there was no significant difference in either HRV indices between them, while heart rate was lower after the true acupuncture than the sham-site stimulation (60.8 ± 1.6 vs. 61.7 ± 1.6 bpm, p < 0.0001). Conclusions: Acupuncture increases parasympathetic HRV indices during sleep, especially during the non-REM stage.