What is the origin of "peace of mind is natural and refreshing"?

Peace of mind refers to a natural peace of mind when dealing with people, things and living alone. Peace of mind is naturally cool, that is, peace of mind and natural cooling of the heart. Later, it was used to refer to dealing with problems in life with a calm mind when encountering problems, difficulties and setbacks.

As the saying goes, "peace of mind is naturally cool", which shows that people's subjective feelings have a certain role. Recently, Tetsuo Yamayama, a physician at Nishimiya Sherry Neurosurgery Hospital in Hyogo Prefecture, Japan, and American scholars have found a certain scientific basis for this phenomenon through experiments.

Dr. Hill took 10 American men and women as the research object. In order to transmit the burning pain to the brain, he used small metal pieces to thermally stimulate the legs and stomach of the subjects. If it is an interval of 15 second, a thermal stimulus of 48 degrees Celsius is used after the start signal, and if it is an interval of 30 seconds, a thermal stimulus of 50 degrees Celsius is used after the start signal. This is repeated many times, so that the subjects can remember the types of stimuli in the brain.

Then, change the type of stimulus, and let the subjects receive a thermal stimulus of 50 degrees Celsius with an interval of 15 seconds. At the same time, magnetic vibration imaging equipment is used to study brain activity. It was found that at the temperature of 50 degrees Celsius every 30 seconds, the activity of emotional areas in the brain was lower than that of thermal stimulation. After the researchers asked the subjects about the degree of pain and made a quantitative analysis, they found that the pain was reduced by about 30%.

Dr. Hill said that this experimental result proved the feeling of "being calm and naturally cool" to some extent. Before the injection, the doctor told the patient that it didn't hurt, which is a scientifically based analgesic method. This achievement has been published in the Proceedings of the National Academy of Sciences.