Conventional laser stimulation at the acupoint can induce significant brain activation, and the activation is theoretically conveyed by the sensory afferents. Whether the insensible low-level Laser stimulation outside the acupoint could also evoke electroencephalographic (EEG) changes is not known. We designed a low-level laser array stimulator (6 pcs laser diode, wavelength 830 nm, output power 7 mW, and operation frequency 10 Hz) to deliver insensible laser stimulations to the palm. EEG activities before, during, and after the laser stimulation were collected. The amplitude powers of each EEG frequency band were analyzed. We found that the low-level laser stimulation was able to increase the power of alpha rhythms and theta waves, mainly in the posterior head regions. These effects lasted at least 15 minutes after cessation of the laser stimulation. The amplitude power of beta activities in the anterior head regions decreased after laser stimulation. We thought these EEG changes comparable to those in meditation.

In our previous study, the low-level laser (LLL) stimulation at the palm with a stimulation frequency of 10 Hz was able to induce significant brain activation in normal subjects. The electroencephalography (EEG) changes caused by the stimulation of light-emitting diode (LED) in normal subjects have not been investigated. This study aimed at identifying the effects of LED stimulation on the human brain using EEG analysis. Moreover, the dosage has been raised 4 times than that in the previous LLL study. The LED array stimulator (6 pcs LEDs, central wavelength 850 nm, output power 30 mW, and operating frequency 10 Hz) was used as the stimulation source. The LED stimulation was found to induce significant variation in alpha activity in the occipital, parietal, and temporal regions of the brain. Compared to the previous low-level laser study, LED has similar effects on EEG in alpha (8–12 Hz) activity. Theta (4–7 Hz) power significantly increased in the posterior head region of the brain. The effect lasted for at least 15 minutes after stimulation ceased. Conversely, beta (13–35 Hz) intensity in the right parietal area increased significantly, and a biphasic dose response has been observed in this study.

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Affecting the brainwave by radiating the palm of the tester with a low-level laser array has been proposed in our previous study. The power of alpha rhythms has been increased mainly in the posterior head regions. The effect lasted at least 15 minutes after cessation of the laser stimulation. However, the effect of non-coherent light (Light Emitting Diode, LED) in similar conditions hasn't been investigated. In this study, a LED array stimulator (6 pcs LEDs, central wavelength 850nm, output power 30mW, operation frequency: 10 Hz) was designed to be the light source. An eyes-open EEG data were recorded during and after stimulation. The experimental results reveal the power of the alpha band has been enhanced with this LED array which operated in 10Hz. Significant activations were found in the parietal lobe 、 the occipital lobe and the temporal lobe (p<0.05). The experimental result reveals that LED almost has the same effect obtained from the laser.

Background: Nowadays people usually have higher work pressure and faster life rhythm. In the long-term stress environment, easily lead to autonomic nervous system (ANS) disorders and lead to physiological or psychological problems. To resolve the problem, we propose an embedded system which integrates ANS monitoring and low energy light stimulation. When the ANS was detected abnormal, a recommended low energy infrared light was activated to stimulate the subject to balance ANS. Materials and Methods: The experiment instruments included electrocardiogram (ECG) module, LED array and the embedded system. ECG module received ECG signal, and then transferred analog signal to digital data. The microprocessor calculated time-domain and frequency-domain data of heart rate variability (HRV), and analyzed the time-domain data, and power spectral density data. The autonomic nervous system (ANS) of the user can be monitored by this device we developed. When the calculated values are out of the criteria, the system will alert the user to turn on infrared light to stimulate and balance ANS. LED wavelength is 850 nm, the default output power is 10 mW, and the default repetition rate is 10 Hz. Result: Wu et al. proposed that using low level laser to stimulate on Neiguan point (PC6) was used to adjust the ANS of the night shift workers. And in other studies, Laser array and LED array were used to stimulate the palm of the subjects with open eyes in different clinical trial, the alpha powers were both increased significantly. So the combination of ANS monitoring and light therapy was useful and feasible. Besides ECG monitoring, LED irradiation and HRV calculation, the data of the embedded system can be transmitted by UART to the remote PC for storage, display and analysis. Furthermore, the embedded system can receive the setting value from PC. For example, adjusting the irradiated dosage, LED operation rate and duty cycle to find out the influence factor of the ANS. Conclusion: an embedded system with ECG monitoring and LED infrared stimulation was realized, it combined physiological state monitoring and light stimulation, it make the ANS feedback and real time adjustment possible.