Heaven possesses the four seasons and five elements, through which all things are born, grow, are harvested, and stored. Traditional Chinese medicine (TCM) holds that human beings are part of nature and should adjust their daily routines in accordance with natural changes to pursue the way of health preservation.

As stated in Huangdi Neijing (Yellow Emperor’s Inner Canon), specifically in Suwen (Plain Questions), chapter Siqi Tiaoshen Dalun (Great Treatise on Regulating the Spirit in Accordance with the Four Qi):

“In the three months of spring, this is the time of effusion and renewal. All things between heaven and earth are born, and all things flourish. One should retire at night and rise early, stroll broadly in the courtyard, let the hair hang loose and relax the body, so that the emotion may grow.” Spring is the season of growth and effusion. People should be active like the newly awakened flora and fauna, maintain a cheerful mood and stable emotions, and engage in appropriate exercise to assist the dispersal of yang qi and prevent the stagnation of qi.

“In the three months of summer, this is the time of luxuriant growth. The qi of heaven and earth mingle, and all things flower and bear fruit. One should retire at night and rise early, not be averse to the sun, and keep the emotion free from anger.” In summer, yang qi reaches its peak. On the one hand, one should follow the abundance of sunlight by rising early and being more active; on the other hand, one must also guard against summer heat by replenishing fluids, preventing the loss of body fluids from excessive perspiration, and nourishing the heart to calm the spirit.

“In the three months of autumn, this is the time of composure and equilibrium. The heavenly qi becomes brisk, and the earthly qi becomes clear. One should retire early and rise early, rising together with the roosting fowl, keeping the emotion peaceful, to temper the severity of autumn, and restraining the spirit and qi.” As the weather grows cooler in autumn, yang qi diminishes while yin qi increases. One should go to bed and rise early to preserve yang qi. Moreover, with the bleak autumn wind and dry climate, one should attend to nourishing yin and moistening dryness, and reduce the consumption of pungent foods to avoid injuring lung qi.

“In the three months of winter, this is the time of closure and storage. Water freezes and the earth cracks. Do not disturb the yang. One should retire early and rise late, awaiting the sun’s light, and keep the emotion as though concealed and hidden.” In winter, yin is predominant and yang is diminished, daylight hours are short, and all things lie dormant. One should go to bed early and rise late, avoid disturbing the yang qi, keep warm, and store the body’s essence in anticipation of the rise of yang qi in spring.