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Dao Han (Night Sweats) refers to sweating during sleep and cessation upon waking. However, Dao Han in miscellaneous diseases is attributed to Yang Deficiency (deficiency of the body's warming and defensive energy). Dao Han in Shanghan (Cold Damage) is caused by pathogenic factors residing at the Half-Exterior and Half-Interior (the Shaoyang stage). Why is this? When pathogenic factors are on the exterior and interfere with the Wei Qi (Defensive Qi), sweating occurs naturally. In this case, pathogenic factors have invaded the interior and connect externally to the exterior. During sleep, Wei Qi travels inward; thus, the Yang Qi on the exterior fails to consolidate, allowing Body Fluids (Jin Ye) to escape, resulting in sweating during sleep. Upon waking, Qi disperses to the exterior, and sweating ceases. Furthermore, while Zi Han (Spontaneous Sweating) can be either deficiency or excess, Dao Han is considered related to the Exterior (Note: The original text states "all known as exterior," which may imply a specific diagnostic context or potential textual error, but translated literally here).

The Head is the convergence point of all Yang meridians. When pathogens contend with Yang Qi and fluids rush upward, sweating appears on the head. If pathogenic heat accumulates internally and steams the Cou Li (skin pores and interstices), causing sweating over the entire body, it is called "Re Yue" (Heat Venting/Dispersal). Now, if Stagnant Heat (Yu Re) is trapped in the interior and cannot vent, but steams upward along the Yang channels, it causes sweating on the head. Why? Because the Three Yin meridians reach the neck and return, not circulating to the head; only the Yang meridians ascend to the head. For those with head sweating due to dryness of the Five Viscera and depletion of fluids, sweating-inducing methods must strictly be avoided. Another view holds that before Jaundice (Huang Dan) manifests, head sweating often appears first; thus, head sweating can be a precursor to Jaundice, and treatment should focus on clearing damp-heat. In cases where water retention causes head sweating, warming and dispersing the water qi is appropriate. If head sweating occurs due to pathology at the Half-Exterior and Half-Interior, harmonizing Ying (Nutritive) and Wei (Defensive) Qi is indicated. Whether due to stagnant heat in the interior, heat entering the Blood Chamber (Xue Shi), or deficiency irritability causing head sweating, emesis or purgation may be used to eliminate the pathogen. However, if urination is difficult, and after a mistaken purgation in a patient with dampness, leading to Yang collapse, the condition becomes incurable.

The hands and feet constitute the four limbs. The limbs are the root of all Yang meridians, and the Stomach governs the limbs. Sweating of the hands and feet is a symptom of Yangming disease. Cases include spontaneous sweating of the whole body, head sweating, and hand-foot sweating, all of which belong to the Yangming pattern. Why? Generalized sweating is termed "Re Yue" (Heat Venting), indicating heat escaping outward. Head-only sweating indicates that heat cannot vent outward but rises upward. Hand-and-foot sweating occurs because heat aggregates in the Stomach, forcing fluids to distribute laterally to the limbs. One might ask: If heat aggregation in the Stomach causes hand-and-foot sweating, does cold aggregation in the Stomach cause no sweating? The Classics state: Accumulated heat leads to dry feces and delirious speech; for hand-and-foot sweating in such cases, Chengqi Tang (Gastrodrinia Decoction) is the primary formula. If accompanied by cold, leading to indistinguishable food and water, cold limbs, and spontaneous sweating, Lizhong Tang (Centrum Decoction) is the primary formula. Thus, there is a distinction between the use of Chengqi Tang and Lizhong Tang.