36. The Principle of Oriental Medicine : The Correspondence Between Heaven and Man

The concept of Cheon-in-sang-eung (天人相應) is interpreted as “the mutual correspondence between Heaven and Man.” Here, Heaven (天) refers to the laws of nature or the universe. It suggests that humans and nature interact, respond, transform, and resemble each other. Unlike Western philosophy, which tends to separate humans from nature and sees nature as an object to be conquered, Eastern paradigms emphasize communion or unity with nature. Therefore, in Oriental medicine, disease prevention and treatment always consider the natural environment, the yin-yang principle, the four seasons, and time. Above all, the principle of “appropriate treatment according to time, place, and individual” (因时、因地、因人制宜) is emphasized.

In Eastern thought, it is believed that the original life force (qi or vibrational wave) of the great universe also flows within humans, who are regarded as microcosms. Hence, “Work when the sun rises and rest when it sets” (日出而作, 日入而息). The human body is designed to follow the rhythms of nature: in the morning, cortisol is secreted to activate the body; at night, growth hormone is released for cellular regeneration, and melatonin is secreted for deep sleep. All of this shows that our body is aligned with the natural order of the sun — this is the essence of Cheon-in-sang-eung.

There’s a Western proverb: “Eat breakfast like a king, lunch like a prince, and dinner like a pauper.” Growth hormone is typically secreted between 10 p.m. and 2 a.m., and it is not secreted when the stomach is full. Therefore, overeating at night suppresses this hormone. Even after puberty, small amounts of growth hormone are released to support cell regeneration.

Melatonin, also known as the “sleep hormone,” promotes deep sleep, but artificial light disrupts its secretion. Thus, it is beneficial to enjoy morning sunlight while minimizing exposure to blue light from smartphones and computers at night.

However, in modern society, where artificial lighting turns night into day, the body’s internal clock can easily become disrupted. When the hormonal balance is disturbed, sleep quality declines. If such conditions persist, various lifestyle diseases may occur. Understanding and aligning with the order of nature is one of the fundamental principles of Oriental medicine.

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Dr. Jin-man Kim, director of Peace Oriental Clinic