According to the natural law, as people age, they will have changes both physically and mentally. Weak health, gray hair, slow walking, hunchback, blurred vision, poor hearing and becoming increasingly irritable are some of the physiological changes in the elderly.

The autonomic nervous system plays an important role in regulating the internal environment, helping the body respond and adapt to changes and impacts from the environment and directly affecting important functions such as heart rate, blood pressure, digestion, respiration, etc.