Department of Health Sciences and Technology, Neural Control of Movement Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, Switzerland.
Department of Cardiology, University Heart Center Zurich, University of Zurich, Zurich, Switzerland.
Sleep. 2022 Sep 8;45(9). doi: 10.1093/sleep/zsac155.
Slow waves, the hallmark feature of deep nonrapid eye movement sleep, do potentially drive restorative effects of sleep on brain and body functions. Sleep modulation techniques to elucidate the functional role of slow waves thus have gained large interest. Auditory slow wave stimulation is a promising tool; however, directly comparing auditory stimulation approaches within a night and analyzing induced dynamic brain and cardiovascular effects are yet missing. Here, we tested various auditory stimulation approaches in a windowed, 10 s ON (stimulations) followed by 10 s OFF (no stimulations), within-night stimulation design and compared them to a SHAM control condition. We report the results of three studies and a total of 51 included nights and found a large and global increase in slow-wave activity (SWA) in the stimulation window compared to SHAM. Furthermore, slow-wave dynamics were most pronouncedly increased at the start of the stimulation and declined across the stimulation window. Beyond the changes in brain oscillations, we observed, for some conditions, a significant increase in the mean interval between two heartbeats within a stimulation window, indicating a slowing of the heart rate, and increased heart rate variability derived parasympathetic activity. Those cardiovascular changes were positively correlated with the change in SWA, and thus, our findings provide insight into the potential of auditory slow wave enhancement to modulate cardiovascular restorative conditions during sleep. However, future studies need to investigate whether the potentially increased restorative capacity through slow-wave enhancements translates into a more rested cardiovascular system on a subsequent day.
慢波是深非快速眼动睡眠的标志特征，它可能对大脑和身体功能的睡眠恢复作用产生影响。因此，睡眠调节技术来阐明慢波的功能作用已经引起了广泛的关注。听觉慢波刺激是一种很有前途的工具；然而，在一个晚上内直接比较听觉刺激方法，并分析诱导的动态大脑和心血管效应仍然缺失。在这里，我们在一个窗口内测试了各种听觉刺激方法，在 10 秒的 ON（刺激）后接着是 10 秒的 OFF（无刺激），进行了夜间内的刺激设计，并将其与 SHAM 对照条件进行了比较。我们报告了三项研究的结果和总共 51 个被纳入的夜晚，结果显示在刺激窗口中与 SHAM 相比，慢波活动（SWA）有较大的整体增加。此外，慢波动力学在刺激开始时最明显增加，并在整个刺激窗口中下降。除了脑电波的变化之外，我们还观察到，在某些情况下，刺激窗口内两个心跳之间的平均间隔显著增加，这表明心率减慢，心率变异性增加，提示副交感神经活动增加。这些心血管变化与 SWA 的变化呈正相关，因此，我们的研究结果提供了有关听觉慢波增强在睡眠期间调节心血管恢复条件的潜力的见解。然而，未来的研究需要调查通过慢波增强增加的潜在恢复能力是否会在随后的一天转化为更休息的心血管系统。
