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The photoplethysmogram (PPG) is currently used to assess the autonomic nervous system in wearable sensors but the PPG also contains additional information about the arterial system and mental state. This knowledge was known by ancient medicinal system, especially those from the Eastern countries. We present a work that combines the Tibetan medicine concepts of three fundamental energies or humours called Tripa, Lung and Beken with modern techniques of PPG signal analysis to derive a holistic view on the state of a person.
To quantify the state of energy balance of a person using PPG and the three energies. The methodology is further validated in the context of mental stress and active breathing relaxation.
Methods and Material
In Study 1, PPG features were computed on 33 subjects to derive the three energies. In Study 2: The energy balance was derived and validated on ten subjects.
Statistical results show that the PPG derived energies are significantly (Student t-tests) different from baseline in stress and relaxation. Energy balance shows a large group variance and exhibit the well-known psychophysiological adaptation process.
We have demonstrated the potential benefit to use PPG to assess the mental and cardiac and vascular state of a person using Tibetan medicine concepts. The energy balance metric can potentially have great value in the assessment of mental state disorders such as anxiety, stress and depression and applied in the context of breathing based relaxation techniques.