The Research Of Sleep Staging And Sleep Induce By Low Frequency Magnetic Field

Sleep is a kind of basic vital activities of human being. Good sleep is helpful to relieve fatigue, restore physical strength, protect cerebrum, and enhance organism immunity. But now, the sleep quality of more and more people are reducing, even more and more people are suffering from the torture of insomnia. Bad sleep harms not only individuals physically and mentally, but also consequently affects society's aspects. Therefore, it will have a significant meaning to explore an insomnia therapy which has good effect to sleep, does not disturb the normal sleeping, is non-addictive and is easily estimated with objective parameters.The appraisal of sleep quality not only lies on the length of sleep time, moreover also on the speed of falling into sleep and the depth of sleep, as well as whether the sleep structure is reasonable. Therefore, the sleep staging becomes the premise in sleep studies, staging by Electroencephalogram(EEG) signal is one of the most important and accurate methods, therefore it requests analyzing and understanding sleep EEG in a deeper level.The main works of this dissertation are as follows:1. Several new characteristics of sleep EEG were analyzed. The difference in sleep patterns of different stages was expressed with the Itakura distance. The complexity of EEG was expressed by the nonlinear sample entropy which showed that the value of sample entropy decreased with sleep's deepening, but the value of the stage of rapid eye movement approached to of stage 1, the change regulation of EEG signal with the scale in different stages was expressed by the multi-scale entropy. It showed that, by the multifractal detrended fluctuation analysis, the sleep EEG was a fractal process and multi-structure existed, but it also displayed de-correlation performance in certain degree.2. In total, 19 characteristic parameters in time domain, frequency domain and nonlinearity were extracted to construct character matrix. The sleep staging accuracy reached 89.1% with three layers structure BP neural network and achieved 92.9% with the multi-classification method classification of support vector machines, and the classification error rates between sleep stage 3 and stage 4, stage 1 and REM reduced greatly.3. Real head model was constructed, and the magnetic distribution in cerebrum induced by low frequency magnetic field was simulated.4. Low frequency magnetic field sleep stimulation experiment was done, and the stimulation effects were comparatively analyzed by objective parameters. The result shows that the sleep latency reduced 9 minutes finally, the total sleep time expands 25 minutes, and the proportion of deep sleep lengthens 9.9%. It shows the effect of low frequency magnetic field to sleep induced. And the low-frequency-magnetic-field action mechanism and the theoretical model were discussed.