Shinar Zvi, Akselrod Solange, Dagan Yaron, Baharav Armanda
Abramson Center for Medical Physics, Tel Aviv University, Tel-Aviv, Israel.
Auton Neurosci. 2006 Dec 30;130(1-2):17-27. doi: 10.1016/j.autneu.2006.04.006. Epub 2006 Jun 8.
Autonomic function during sleep and wakefulness has been extensively investigated, however information concerning autonomic changes during the wake to sleep transition is scarce. The objective of the present study was to non-invasively characterize autonomic function and additional physiologic changes during sleep onset in normal and abnormal sleep. The estimation of autonomic function was based on time-frequency analysis of the RR interval series, using the power components in the very-low-frequency range (0.005-0.04 Hz), low-frequency (0.04-0.15 Hz), and high-frequency range (0.15-0.5 Hz). The ratio of low to high frequency power represented the sympathovagal balance. Thirty-four subjects who underwent whole night polysomnography were divided into 3 groups according to their complaints and study results: normal subjects, apneic patients (OSAS), and subjects with various sleep disorders (VSD). The results indicated a significant increase in RR interval during sleep onset, although its variability decreased; respiratory rate did not change, yet respiration became more stable; EMG amplitude and its variability decreased with sleep onset. Very-low-frequency power started to decrease significantly 2 min before sleep onset in all groups; low-frequency power decreased and high-frequency power did not change significantly in all groups, accordingly their ratio decreased and reflected a shift towards parasympathetic predominance. Although autonomic function displayed similar behavior in all subjects, OSAS and VSD patients presented a higher sympathovagal balance reflecting enhanced sympathetic predominance in those groups compared to normal subjects, both before and after sleep onset. All parameters reached a nadir at a defined time point during the process of falling asleep. We conclude that the wake-sleep transition period represents a transitional process between two physiologically different states; this transition starts with a decrease in the very slow oscillations in heart rate that anticipates a step-change resetting of autonomic function, followed by a decrease in sympathovagal balance towards the end of the process.
睡眠和清醒期间的自主神经功能已得到广泛研究，然而，关于从清醒到睡眠过渡期间自主神经变化的信息却很少。本研究的目的是在正常睡眠和异常睡眠中，以非侵入性方式描述睡眠开始期间的自主神经功能及其他生理变化。自主神经功能的评估基于RR间期序列的时频分析，使用极低频范围（0.005 - 0.04Hz）、低频（0.04 - 0.15Hz）和高频范围（0.15 - 0.5Hz）的功率成分。低频与高频功率之比代表交感迷走神经平衡。34名接受整夜多导睡眠图检查的受试者根据其主诉和研究结果分为3组：正常受试者、呼吸暂停患者（阻塞性睡眠呼吸暂停低通气综合征）和患有各种睡眠障碍的受试者（各种睡眠障碍）。结果表明，睡眠开始时RR间期显著增加，但其变异性降低；呼吸频率未改变，但呼吸变得更稳定；肌电图幅度及其变异性随着睡眠开始而降低。在所有组中，极低频功率在睡眠开始前2分钟开始显著下降；低频功率下降，高频功率在所有组中无显著变化，因此它们的比值下降，反映出向副交感神经占优势的转变。尽管所有受试者的自主神经功能表现相似，但阻塞性睡眠呼吸暂停低通气综合征和各种睡眠障碍患者在睡眠开始前后的交感迷走神经平衡均高于正常受试者，反映出这些组中交感神经占优势增强。所有参数在入睡过程中的特定时间点达到最低点。我们得出结论，清醒 - 睡眠过渡期代表了两种生理状态不同的状态之间的过渡过程；这种过渡始于心率非常缓慢的振荡减少，这预示着自主神经功能的阶跃变化重置，随后在过程结束时交感迷走神经平衡降低。
