Biomedical Optics Research Laboratory, Division of Neonatology, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.
Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland.
Adv Exp Med Biol. 2013;789:113-119. doi: 10.1007/978-1-4614-7411-1_16.
How does the oxygen metabolism change during sleep? We aimed to measure the change in brain tissue oxygen saturation (StO2) before and after sleep with near-infrared spectroscopy (NIRS) using an in-house developed sensor. According to the synaptic homeostasis hypothesis [1], synaptic downscaling during sleep would result in reduced energy consumption. Thus, this reduced energy demands should be reflected in the oxygen metabolism and StO2. Thirteen nights of 7 male subjects (age 11-16 years, one subject contributed only one night, all others two) were included in the analysis. We performed NIRS measurements throughout the entire night. The NIRS sensor was placed close to electrode position Fp1 (international 10/20 system), over the left frontal cortex. Absolute StO2 and total haemoglobin (tHb) were calculated from the NIRS measurements using a self-calibrating method [2]. StO2 and tHb during the awake period prior to sleep and after awakening were compared. The subjects were instructed to lie in bed in the same position before and after sleep. Values of the two nights were averaged for each subject. Furthermore, a linear regression line was fit through the all-night StO2 recordings. We found an increase in StO2 by 4.32 ± 1.76 % (mean ± SD, paired t-test p < 0.001, n = 7) in the morning compared to evening, while tHb did not change (1.02 ± 6.81 μM p = 0.704, n = 7). Since the tHb remained at a similar level after sleep, this increase in StO2 indicates that in the morning more oxygenated blood and less deoxygenated blood was present in the brain compared to the evening. The slope of the regression line was 0.37 ± 0.13 % h(-1) leading to a similar increase of StO2 in the course of sleep. This may be interpreted as a reduced oxygen consumption or energy metabolism after sleep.
睡眠期间氧代谢如何变化？我们旨在使用自主研发的传感器，通过近红外光谱（NIRS）测量睡眠前后脑组织氧饱和度（StO2）的变化。根据突触稳态假说[1]，睡眠期间的突触下调会导致能量消耗减少。因此，这种能量需求的减少应该反映在氧代谢和 StO2 中。分析纳入了 13 名男性受试者（年龄 11-16 岁，其中 1 名受试者仅贡献了 1 个晚上，其余受试者均贡献了 2 个晚上）。我们整夜进行了 NIRS 测量。NIRS 传感器放置在靠近电极位置 Fp1（国际 10/20 系统）的左侧额叶附近。使用自校准方法[2]从 NIRS 测量值计算绝对 StO2 和总血红蛋白（tHb）。比较了睡前和觉醒后清醒期的 StO2 和 tHb。指导受试者在睡前和睡后保持相同的体位躺在床上。每个受试者的两晚值平均化。此外，通过整夜 StO2 记录拟合线性回归线。我们发现，与晚上相比，早上 StO2 增加了 4.32±1.76%（平均值±标准差，配对 t 检验 p<0.001，n=7），而 tHb 没有变化（1.02±6.81 μM，p=0.704，n=7）。由于 tHb 在睡眠后保持在相似水平，因此 StO2 的增加表明与晚上相比，早上大脑中含氧血液增加，脱氧血液减少。回归线的斜率为 0.37±0.13%h-1，导致睡眠过程中 StO2 相似程度的增加。这可以解释为睡眠后氧消耗或能量代谢减少。
