{"title":"Can the Brain's Thermostatic Mechanism Generate Sleep-Wake and NREM-REM Sleep Cycles? A Nested Doll Model of Sleep-Regulating Processes.","authors":"Arcady A Putilov","doi":"10.3390/clockssleep6010008","DOIUrl":null,"url":null,"abstract":"<p><p>Evidence is gradually accumulating in support of the hypothesis that a process of thermostatic brain cooling and warming underlies sleep cycles, i.e., the alternations between non-rapid-eye-movement and rapid-eye-movement sleep throughout the sleep phase of the sleep-wake cycle. A mathematical thermostat model predicts an exponential shape of fluctuations in temperature above and below the desired temperature setpoint. If the thermostatic process underlies sleep cycles, can this model explain the mechanisms governing the sleep cyclicities in humans? The proposed nested doll model incorporates Process s generating sleep cycles into Process S generating sleep-wake cycles of the two-process model of sleep-wake regulation. Process s produces ultradian fluctuations around the setpoint, while Process S turns this setpoint up and down in accord with the durations of the preceding wake phase and the following sleep phase of the sleep-wake cycle, respectively. Predictions of the model were obtained in an <i>in silico</i> study and confirmed by simulations of oscillations of spectral electroencephalographic indexes of sleep regulation obtained from night sleep and multiple napping attempts. Only simple-inverse exponential and exponential-functions from the thermostatic model were used for predictions and simulations of rather complex and varying shapes of sleep cycles during an all-night sleep episode. To further test the proposed model, experiments on mammal species with monophasic sleep are required. If supported, this model can provide a valuable framework for understanding the involvement of sleep-wake regulatory processes in the mechanism of thermostatic brain cooling/warming.</p>","PeriodicalId":33568,"journal":{"name":"Clocks & Sleep","volume":null,"pages":null},"PeriodicalIF":2.1000,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10885066/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Clocks & Sleep","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3390/clockssleep6010008","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CLINICAL NEUROLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Evidence is gradually accumulating in support of the hypothesis that a process of thermostatic brain cooling and warming underlies sleep cycles, i.e., the alternations between non-rapid-eye-movement and rapid-eye-movement sleep throughout the sleep phase of the sleep-wake cycle. A mathematical thermostat model predicts an exponential shape of fluctuations in temperature above and below the desired temperature setpoint. If the thermostatic process underlies sleep cycles, can this model explain the mechanisms governing the sleep cyclicities in humans? The proposed nested doll model incorporates Process s generating sleep cycles into Process S generating sleep-wake cycles of the two-process model of sleep-wake regulation. Process s produces ultradian fluctuations around the setpoint, while Process S turns this setpoint up and down in accord with the durations of the preceding wake phase and the following sleep phase of the sleep-wake cycle, respectively. Predictions of the model were obtained in an in silico study and confirmed by simulations of oscillations of spectral electroencephalographic indexes of sleep regulation obtained from night sleep and multiple napping attempts. Only simple-inverse exponential and exponential-functions from the thermostatic model were used for predictions and simulations of rather complex and varying shapes of sleep cycles during an all-night sleep episode. To further test the proposed model, experiments on mammal species with monophasic sleep are required. If supported, this model can provide a valuable framework for understanding the involvement of sleep-wake regulatory processes in the mechanism of thermostatic brain cooling/warming.
越来越多的证据支持这样一种假设,即大脑恒温的冷却和升温过程是睡眠周期的基础,即在睡眠-觉醒周期的整个睡眠阶段,非快速眼动睡眠和快速眼动睡眠之间的交替。恒温器的数学模型预测,温度在所需温度设定点上下的波动呈指数形状。如果恒温过程是睡眠周期的基础,那么这个模型能否解释人类的睡眠周期机制呢?所提出的嵌套娃娃模型将产生睡眠周期的过程 s 纳入了睡眠-觉醒双过程调节模型中产生睡眠-觉醒周期的过程 S 中。过程 s 围绕设定点产生超昼夜波动,而过程 S 则分别根据睡眠-觉醒周期中前一个觉醒阶段和后一个睡眠阶段的持续时间上下调整该设定点。该模型的预测是在一项硅学研究中获得的,并通过模拟夜间睡眠和多次小睡尝试中获得的睡眠调节频谱脑电图指标的振荡得到了证实。只有恒温模型中的简单反指数函数和指数函数被用于预测和模拟整夜睡眠过程中复杂多变的睡眠周期。为了进一步验证所提出的模型,需要在单相睡眠的哺乳动物物种上进行实验。如果得到支持,该模型将为理解恒温大脑降温/升温机制中睡眠-觉醒调节过程的参与提供一个有价值的框架。