School of Psychological Sciences and Turner Institute for Brain and Mental Health, Monash University, 3800, Clayton, Australia; Cooperative Research Centre for Alertness, Safety and Productivity, 3800, Australia.
Sleep and Respiratory Care, Philips, Pittsburgh, PA, USA; Department of Psychiatry, University of Wisconsin-Madison, WI, USA.
Sleep Med. 2021 May;81:69-79. doi: 10.1016/j.sleep.2021.01.044. Epub 2021 Jan 30.
Chronic sleep restriction has been linked to occupational errors and motor vehicle crashes. Enhancing slow wave sleep may alleviate some of the cognitive deficits associated with chronic sleep restriction. However, the extent to which acoustic stimulation of slow wave activity (SWA) may improve alertness and attention is not well established, particularly with respect to consecutive nights of exposure.
Twenty-five healthy adults (32.9 ± 8.2 years; 16 female) who self-restricted their sleep during workdays participated in a randomized, double-blind, cross-over study. Participants wore an automated acoustic stimulation device for two consecutive nights. Acoustic tones (50 ms long) were delivered on the up-phase of the slow wave first and then at constant 1-s inter-tone-intervals once N3 was identified (STIM), until an arousal or shift to another sleep stage occurred, or at inaudible decibels during equivalent stimulation periods (SHAM). Subjective alertness/fatigue (KSS, Samn-Perelli) was assessed across both days, and objective measures of alertness (MSLT) and attention (PVT) were assessed after two nights of stimulation.
After one night of acoustic stimulation, increased slow wave energy was observed in 68% of participants, with an average significant increase of 17.7% (p = 0.01), while Night 2 was associated with a 22.2% increase in SWA (p = 0.08). SWE was highly stable across the two nights of STIM (ICC 0.93, p < 0.001), and around half (56%) of participants were consistently classified as responders (11/25) or non-responders (3/25). Daytime testing showed that participants felt more alert and awake following each night of acoustic stimulation (p < 0.05), with improved objective attention across the day following two nights of acoustic stimulation.
Consecutive nights of acoustic stimulation enhanced SWA on both nights, and improved next day alertness and attention. Given large individual differences, we highlight the need to examine both the long-term effects of stimulation, and to identify inter-individual differences in acoustic stimulation response. Our findings suggest that the use of an acoustic device to enhance slow wave sleep may alleviate some of the deficits in alertness and attention typically associated with sleep restriction.
慢性睡眠限制与职业失误和机动车事故有关。增强慢波睡眠（SWS）可能会缓解与慢性睡眠限制相关的一些认知缺陷。然而，声刺激慢波活动（SWA）在多大程度上可以提高警觉性和注意力尚不清楚，特别是对于连续几晚的暴露。
25 名健康成年人（32.9±8.2 岁；16 名女性）在工作日期间自行限制睡眠，参加了一项随机、双盲、交叉研究。参与者在连续两个晚上佩戴自动声刺激装置。在识别出 N3 后，声刺激（50ms 长）首先在慢波的上升阶段发出，然后以恒定的 1 秒间隔发出，直到出现觉醒或转移到另一个睡眠阶段，或者在相当的刺激期间以听不到的分贝发出（STIM）。在两天内评估主观警觉性/疲劳（KSS、Samn-Perelli），并在两个晚上的刺激后评估客观警觉性（MSLT）和注意力（PVT）。
在一夜的声刺激后，68%的参与者观察到慢波能量增加，平均显著增加 17.7%（p=0.01），而第二晚 SWA 增加 22.2%（p=0.08）。在 STIM 的两个晚上，SWE 高度稳定（ICC 0.93，p<0.001），大约一半（56%）的参与者被一致归类为应答者（11/25）或非应答者（3/25）。白天测试表明，参与者在每夜声刺激后感觉更警觉和清醒（p<0.05），在连续两晚声刺激后全天注意力提高。
连续几晚的声刺激在两晚都增强了 SWA，并改善了第二天的警觉性和注意力。鉴于个体差异较大，我们强调需要检查刺激的长期影响，并确定个体对声刺激反应的差异。我们的发现表明，使用声设备来增强慢波睡眠可能会缓解与睡眠限制相关的警觉性和注意力缺陷。
