Ehrhart J, Toussaint M, Simon C, Gronfier C, Luthringer R, Brandenberger G
Laboratoire des Regulations Physiologiques et des Rythmes Biologiques chez l'Homme, 4, rue Kirschleger, 67085, Strasbourg, France.
Clin Neurophysiol. 2000 May;111(5):940-6. doi: 10.1016/s1388-2457(00)00247-9.
We examined simultaneously alpha activity and cardiac changes during nocturnal sleep, in order to differentiate non-rapid eye movement (NREM) sleep, REM sleep, and intra-sleep awakening.
Ten male subjects displaying occasionally spontaneous intra-sleep awakenings underwent EEG and cardiac recordings during one experimental night. The heart rate and heart rate variability were calculated over 5 min periods. Heart rate variability was estimated: (1) by the ratio of low frequency (LF) to high frequency (HF) power calculated from spectral analysis of R-R intervals; and (2) by the interbeat autocorrelation coefficient of R-R intervals (rRR). EEG spectral analysis was performed using a fast Fourier transform algorithm.
Three types of relationships between alpha waves (8-13 Hz) and cardiac correlates could be distinguished. During NREM sleep, alpha activity and cardiac correlates showed opposite variations, with high levels of alpha power associated with decreased heart rate, rRR and LF/HF ratio, indicating low sympathetic activity. Conversely, during REM sleep, alpha activity was low whereas heart rate, rRR, and the LF/HF ratio peaked, indicating high sympathetic activity. During intra-sleep awakenings, alpha activity and cardiac correlates both increased. No difference in time-course between alpha 1 (8-10 Hz) and alpha 2 (10-13 Hz) activity could be shown. Alpha waves occurred in fronto-central areas during slow wave sleep (SWS), migrated to posterior areas during REM sleep, and were localized in occipital areas during intra-sleep awakenings.
These results suggest that alpha waves are not simply a sign of arousal, as is commonly thought. Fronto-central alpha waves, associated with decreased heart rate, possibly reflect sleep-maintaining processes.
我们同时检测了夜间睡眠期间的α波活动和心脏变化，以区分非快速眼动（NREM）睡眠、快速眼动（REM）睡眠和睡眠中觉醒。
10名偶尔出现睡眠中自发觉醒的男性受试者在一个实验夜间接受了脑电图（EEG）和心脏记录。心率和心率变异性在5分钟时间段内进行计算。心率变异性通过以下方式估计：（1）根据RR间期的频谱分析计算低频（LF）与高频（HF）功率之比；（2）通过RR间期的逐搏自相关系数（rRR）。EEG频谱分析使用快速傅里叶变换算法进行。
α波（8-13Hz）与心脏相关指标之间可区分出三种类型的关系。在NREM睡眠期间，α波活动与心脏相关指标呈现相反变化，α波功率高与心率、rRR和LF/HF比值降低相关，表明交感神经活动低。相反，在REM睡眠期间，α波活动低，而心率、rRR和LF/HF比值达到峰值，表明交感神经活动高。在睡眠中觉醒期间，α波活动和心脏相关指标均增加。α1（8-10Hz）和α2（10-13Hz）活动在时间进程上无差异。α波在慢波睡眠（SWS）期间出现在额中央区域，在REM睡眠期间迁移到后部区域，在睡眠中觉醒期间定位于枕部区域。
这些结果表明，α波并非如通常所认为的那样仅仅是觉醒的标志。与心率降低相关的额中央α波可能反映了维持睡眠的过程。
