Achermann P, Dijk D J, Brunner D P, Borbély A A
Institute of Pharmacology, University of Zürich, Switzerland.
Brain Res Bull. 1993;31(1-2):97-113. doi: 10.1016/0361-9230(93)90016-5.
EEG slow-wave activity (SWA; spectral power in the 0.75-4.5 Hz band) is a function of the duration of prior waking and, thereby, an indicator of sleep homeostasis. We present a model that accounts for both the declining trend of SWA during sleep and for its variation within the successive nonrapid eye movement (non-REM) sleep episodes. The values of the model parameters were estimated by an optimization procedure in which empirical SWA of baseline nights (16 subjects, 26 nights) served as a reference. A sensitivity analysis revealed the model to be quite robust to small changes (+/- 5%) of the parameter values. The estimated parameter values were used to simulate data sets from three different experimental protocols (sleep in the evening or sleep in the morning after prolonged waking, or extended sleep initiated at the habitual bedtime; n = 8 or 9). The timing of the REM trigger parameter was derived from the empirical data. A close fit was obtained between the simulated and empirical SWA data, and even the occasional late SWA peaks during extended sleep could be reproduced. Minor discrepancies suggest indirect or direct circadian influences on SWA. The simulations demonstrate that the concept of sleep homeostasis as proposed in the two-process model of sleep regulation can be refined to account in quantitative terms for empirical data and to predict the changes induced by the prolongation of waking or sleep.
脑电图慢波活动（SWA；0.75 - 4.5赫兹频段的频谱功率）是先前清醒时长的函数，因此是睡眠稳态的一个指标。我们提出了一个模型，该模型既考虑了睡眠期间SWA的下降趋势，也考虑了其在连续非快速眼动（non - REM）睡眠阶段内的变化。模型参数值通过一种优化程序进行估计，其中以基线夜（16名受试者，26个夜晚）的经验性SWA作为参考。敏感性分析表明，该模型对参数值的小幅度变化（±5%）相当稳健。估计的参数值用于模拟来自三种不同实验方案的数据集（长时间清醒后晚上睡眠或早上睡眠，或在习惯就寝时间开始的延长睡眠；n = 8或9）。快速眼动触发参数的时间是从经验数据中得出的。模拟的SWA数据与经验性SWA数据之间获得了紧密拟合，甚至延长睡眠期间偶尔出现的较晚SWA峰值也能够被重现。微小差异表明昼夜节律对SWA存在间接或直接影响。模拟结果表明，睡眠调节双过程模型中提出的睡眠稳态概念可以得到完善，以便从定量角度解释经验数据，并预测由清醒或睡眠延长所引起的变化。
