In the natural cycle of spring, summer, autumn, and winter, the seasons change and repeat. Professor Li Jingxiao, a mentor in the National Inheritance Program for the Academic Experience of Senior TCM Experts and a professor at Heilongjiang University of Chinese Medicine, points out that the alternation of the four seasons is the fundamental cause of the growth and storage changes of all things in the world, while the waxing and waning of Yin and Yang is the original source of the formation of seasonal orders. As the saying goes, “The human body is a small universe, and the universe is a large human body.” From ancient times to the present, traditional Chinese medicine (TCM) culture has always emphasized adjusting daily life according to the laws of Yin and Yang changes in the four seasons to maintain the balance of Yin and Yang in the human body, which is the true essence of health preservation.
Professor Li Jingxiao notes that without our realizing it, spring is gradually fading, and summer has arrived. Methods of health preservation and adjustment should also change in accordance with the time to adapt to the rules of Yin and Yang changes in summer. The classic TCM text The Yellow Emperor's Inner Canon contains abundant wisdom for health preservation, providing strong guidance for disease prevention and longevity. It proposes: “During the three months of summer, this is called the flourishing period. Heaven and earth's qi intermingle, and all things flourish and bear fruit. Go to bed late and rise early, do not tire of the sun. Keep your spirit from anger, let the beauty and brilliance come into full bloom, allow the qi to be released, as if what you love is outside. This is the response to the summer qi, the method of nourishing growth.”
Summer is the season when Yang qi rises and Yin qi weakens. The Yang and Yin qi of heaven and earth intermingle, and all things receive ample sunlight, showing an active state of growth and metabolism. It is the season when all things are lush and beautiful, the season for nourishing “growth.” Therefore, the general principle of health preservation during this time must conform to the characteristics of the summer season, focusing on adapting to the vigorous dispersion of Yang qi to nourish “growth,” allowing the body's vital energy to thrive and the physique to become robust and strong.
Going to Bed Late and Rising Early with Moderation
Professor Li Jingxiao emphasizes that in the sweltering heat of summer, when Yang heat is flourishing, the pores of the human body are mostly open, and there is relatively more sweating. This is a self-regulatory mechanism by which the body maintains Yang heat without overexertion. Therefore, The Yellow Emperor's Inner Canon states that one should “not tire of the sun” during this time, meaning that one should not avoid movement due to the heat but should engage in appropriate labor and exercise to maintain moderate sweating.
It is important to note that while sweating is appropriate in summer, excessive sweating is not advisable. Professor Li explains: “Sweat is the fluid of the Heart, produced by the evaporation of Yin fluids through the action of Yang qi. If one stays in a high-temperature or excessively sunny environment for too long, or engages in excessive physical activity, causing excessive sweating, it can easily deplete body fluids and consume qi, leading to feelings of fatigue, drowsiness, and thirst. From a Western medical perspective, excessive sweating can also increase blood viscosity, making it easier to develop cardiovascular diseases.”
Therefore, physical labor and exercise in summer should be regulated, adhering to the principles of slowness, light sweating, and sun protection, avoiding excessive sweating. At the same time, one should not shun sweating and seek coolness excessively, such as staying in air-conditioned rooms with low temperatures or taking cold showers, as this can easily allow wind-cold pathogenic factors to invade the skin, muscles, bones, and even internal organs through the open pores, obstructing Yang qi and blocking the meridians, leading to symptoms like facial paralysis, joint pain, and vomiting and diarrhea. Although it may provide temporary relief, it can have countless aftereffects.
In addition, since summer days are longer and nights shorter, with more daylight hours, one should follow nature's law by “going to bed late and rising early,” which means that the time of going to sleep can be delayed appropriately, but it is still preferable to go to bed before the peak of Yin qi at midnight (from 11 PM to 1 AM), to nourish Yang qi. One should wake up earlier, possibly at dawn (from 5 AM to 7 AM) when nature's Yang qi begins to rise, to assist Yang qi. Professor Li Jingxiao points out that due to the relatively shorter nighttime sleep, taking a nap of 20-30 minutes during the midday in summer is beneficial for eliminating fatigue, restoring strength, maintaining vigor, and reducing the risk of going out at noon when the heat is intense, preventing damage to the body's vital energy by scorching heat.
Mental Adjustment and Calming the Heart
The Heart stores the spirit and corresponds to summer. In the hot summer, the weather is sultry and stuffy, and the Heart's Yang qi can easily become hyperactive and generate fire due to the influence of summer heat, disturbing the spirit. Furthermore, since sweat is the fluid of the Heart, and the heat of summer causes the external secretion of sweat, it can easily consume Heart Yin, leading to malnourishment of the spirit. As a result, people's spirits are easily disturbed in summer, manifesting as irritability. From a Western medical perspective, emotional fluctuations combined with hot and humid weather can reduce the oxygen partial pressure in the blood, causing compensatory increases in breathing frequency and heart rate, potentially triggering myocardial ischemia, arrhythmia, and elevated blood pressure. It can be seen that summer is a time when particular attention should be paid to nourishing the Heart, and nurturing the Heart requires a focus on regulating the spirit.
The Yellow Emperor's Inner Canon suggests that during summer, one should “keep the spirit from anger,” meaning to calm the mind and spirit, avoiding sudden outbursts of anger, so that the spirit is clear and the qi harmonious, allowing for smooth circulation. Therefore, in the scorching heat of summer, one can appropriately adjust work plans and the pace of life, take leisurely walks, play bamboo flutes, or engage in other activities that cultivate the mind and spirit, ensuring a harmonious disposition and sufficient spirit. This allows for coordination of bodily functions, the free flow of Yang qi, and the nourishment of the Heart. From a Western medical perspective, a peaceful mood helps slow down the heart rate and metabolic rate, facilitating a reduction in body temperature, which is why people often say “a calm mind naturally cools.”
Avoid Excessive Consumption of Cold Foods and Moderate Intake
According to Professor Li Jingxiao, in summer, nature is filled with Yang heat, and the body's Yang heat qi tends to rise and flourish on the surface of the body. Therefore, feeling warm and sweating are manifestations of Yang qi dispersing outward in accordance with nature. In daily life, drinking cold beverages in moderation can help prevent heatstroke and lower body temperature. However, indulging in cold foods and drinks can have endless harm. There are two reasons for this: first, cold foods and drinks block the Yang qi that desires to disperse outward, although they achieve the goal of reducing sweating, the normal body fluids get trapped inside the body when they should be sweating but cannot, leading to the production of pathological products like dampness and phlegm, which can cause symptoms like chest tightness, abdominal distension, and loose stools. Second, Yang qi rises to the surface of the body, while Yin qi lies dormant within the organs. The spleen and stomach are already relatively lacking in warmth, and adding cold foods and drinks is like adding frost to snow, easily weakening the Yang qi of the spleen and stomach, damaging their function, and causing symptoms like loss of appetite, fatigue, and listlessness. Therefore, in the sweltering heat of summer, one should “guard against summer heat and also guard against seeking coolness due to the heat” (Li Xu Yuan Jian). Diet should be warm rather than cold to protect the spleen and stomach and nourish Yang qi. This is also why TCM health preservation always emphasizes “nourishing Yang in spring and summer,” and there is a popular saying that “eat radishes in winter and ginger in summer.”
Moreover, the hot weather in summer, with its abundant rainfall and high humidity, aligns with the TCM concept that “summer heat often comes with dampness.” According to TCM, the spleen prefers dryness and dislikes dampness. The damp heat of summer is most likely to burden and injure the spleen, causing digestive disorders, gastrointestinal inflammation, dysentery, and other gastrointestinal diseases. On the contrary, regulating the function of the spleen and stomach can help transform dampness, benefiting health preservation and disease prevention in summer.
Professor Li Jingxiao believes that in summer, protecting the spleen and stomach requires eating in moderation and