Virtanen Irina, Ekholm Eeva, Polo-Kantola Päivi, Huikuri Heikki
Department of Clinical Neurophysiology, University of Turku, Finland.
Auton Neurosci. 2007 Jul 31;134(1-2):74-80. doi: 10.1016/j.autneu.2007.01.010. Epub 2007 Feb 26.
To study the effects of sleep stage changes on nocturnal nonlinear heart rate variability (HRV) in postmenopausal women.
A prospective study.
Seventy-one healthy postmenopausal women.
The women underwent two separate sleep studies four months apart. One steady state epoch per night of the awake state, stage 2 (light) non-REM sleep, stage 3-4 (deep) non-REM sleep and REM sleep were extracted. From the ECG, the fractal scaling exponents alpha(1) and alpha(2), approximate entropy (ApEn), the Poincaré plot variability coefficients SD1 and SD2, along with the low (LF) and high frequency (HF) bands of linear HRV as well as the LF/HF ratio were calculated.
None of the spectral measures of HRV changed significantly during the non-REM sleep compared to awake state. However, in non-REM sleep, alpha(2) (p<0.001) decreased significantly compared to the awake state, while alpha(1) and ApEn remained unchanged. SD1 was slightly increased in stage 2 sleep (p<0.05), while SD2 decreased in slow wave sleep (p<0.001). In REM sleep, alpha(2) values returned to the awake values, while ApEn and alpha(1) increased above the awake levels (p<0.01 for all variables), and SD1 decreased (p<0.01). HF spectral component decreased slightly (p<0.05 compared to stage 2 sleep) and LF/HF ratio increased during REM sleep (p<0.001). ApEn and alpha(2) had no correlations with any of the spectral measures of HRV, and alpha(1) had a modest correlation with the LF/HF ratio only during sleep.
We found that nonlinear indices of HRV describe specific features in HR dynamics during various sleep stages that are not detected by traditional spectral HRV indices.
研究绝经后女性睡眠阶段变化对夜间非线性心率变异性（HRV）的影响。
一项前瞻性研究。
71名健康绝经后女性。
这些女性在相隔四个月的时间里进行了两项独立的睡眠研究。每晚从清醒状态、2期（浅）非快速眼动睡眠、3-4期（深）非快速眼动睡眠和快速眼动睡眠中各提取一个稳态时段。从心电图中计算分形标度指数α(1)和α(2)、近似熵（ApEn）、庞加莱图变异系数SD1和SD2，以及线性HRV的低频（LF）和高频（HF）频段以及LF/HF比值。
与清醒状态相比，非快速眼动睡眠期间HRV的频谱指标均无显著变化。然而，在非快速眼动睡眠中，α(2)（p<0.001）与清醒状态相比显著降低，而α(1)和ApEn保持不变。SD1在2期睡眠中略有增加（p<0.05），而SD2在慢波睡眠中降低（p<0.001）。在快速眼动睡眠中，α(2)值恢复到清醒值，而ApEn和α(1)升高至高于清醒水平（所有变量p<0.01），且SD1降低（p<0.01）。HF频谱成分略有下降（与2期睡眠相比p<0.05），且快速眼动睡眠期间LF/HF比值升高（p<0.001）。ApEn和α(2)与HRV的任何频谱指标均无相关性，且α(1)仅在睡眠期间与LF/HF比值有适度相关性。
我们发现HRV的非线性指标描述了不同睡眠阶段HR动态中的特定特征，而传统频谱HRV指标未检测到这些特征。
