Development of dynamic feedback system to improve sleep environment by means of signal of autonomic nerve activity

为了改善睡眠深度和睡眠时的心脏副交感神经活动，以及早晨的主观睡眠质量，我们进行了实验，开发和验证了一种动态反馈控制系统，该系统通过RR间期变异性的频谱分析，定期反馈信号来调节卧室环境温度。系统的运行原理基于以下三个观察结果，这三个观察来自于对卧室温度的顺序控制对睡眠深度和RR间期变异性的影响的研究。我们考察了28℃恒温和U型控温的两个卧室环境(受试者7人)的心电图或脑电的差异。在结果中，我们观察到(1)两个水平的RR间期变异频谱功率的高频段(HF，0.15-0.4赫兹，单位：毫秒^2)，这是已知的代表心脏副交感神经活动时，睡眠…反映睡眠深度的增量频段(δ，0.5-4 HZ，单位：μV^2)的脑电波功率随温度的变化而变化。(2)当睡眠时改变房间温度时，HF和δ有时同向增加和减少，然而，(3)房间温度与HF或δ的关系因个体而异，甚至在个体开始睡眠后的小时内也是如此。然后，当HF增加时，每隔5分钟将温度升高1℃，而当HF减少时，将相反方向的温度改变相同的程度。以三种恒温睡眠实验(22℃、25℃和28℃)为对照。为了验证动态反馈系统的效果，比较了睡眠期间HF和δ的所有这些转变。当室温保持在22℃、25℃或28℃时，整个睡眠的平均HF在22℃时最高，28℃时最低，而平均δ在28℃时最高，22℃时最低(受试者为10人)。当使用本研究开发的反馈系统时，HF和δ8的平均值都比25℃时高出10%或更多，尽管不同类型的温控人员早上的主观睡眠质量有所不同。在反馈系统下实现的平均室温低于25℃。本研究为睡眠热环境动态反馈控制系统的实用化迈出了一步。较少

In order to improve sleep depth and cardiac parasympathetic nerve activity while sleeping and subjective sleep quality in the morning, we undertook experiments to develop and verify a dynamic feed-back control system that signals by means of spectral analysis of RR interval variability were fed back at regular time intervals to adjust bedroom ambient temperature.The principle of system operation tested here was based on the following three observations which were derived from a study on the effect of sequential control of bedroom temperature on the sleep depth and RR interval variability. We examined the differences of electrocardiogram or electroencephalogram between two bedroom environments with 28℃ constant and U-shaped controlled temperatures (number of subjects were 7). In the results, we observed (1) both levels of RR interval variability spectrum power of high frequency band (HF, 0.15-0.4Hz, unit : msec^2), which is known to represent cardiac parasympathetic activity while sleep … More ing, and of brain wave spectral power of delta band (δ, 0.5-4Hz, unit : μV^2), which is known to represent sleep depth, were depend on the room temperature, (2) HF and δ sometimes increased and decreased in the same direction when the room temperature was changed while sleeping, however, (3) the relationships between room temperature and HF or δ were suggested to differ considerably in individuals, as well as in the elapsed hours after the onset of sleep even in an individual.With these observations, we constructed a feed-back system of ambient temperature that starts from neutral temperature (25℃), then, every 5 minutes, increases temperature by 1℃ when HF has increased, and changed temperature by same degree in the counter direction when HF has decreased. Sleep experiments with three constant room temperatures (22℃, 25℃, and 28℃) were set as control ones. To confirm the effect of the dynamic feed-back system, all these transitions of HF and δ during sleep were compared. Relative humidity has been adjusted to 50% during sleep.When room temperature was kept constant at 22℃, 25℃, or 28℃, average HF over whole sleep was highest at 22℃ and lowest at 28℃, while average δ was highest at 28℃ and lowest at 22℃ (number of subjects were 10). When the feed-back system developed in the study was operated, both average values of HF and δ8 were higher by 10% or more than those at 25℃, although subjective sleep quality in the morning differed between the types of thermal control. The average room temperature achieved under the feed-back system was lower than 25℃. The present study showed a step toward the practical use of dynamic feed-back control system of thermal environment during sleep. Less