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Night is dominated by Yin Qi. When Yin Qi is abundant, the eyes close and one sleeps peacefully. If Yin deficiency allows Yang to prevail, one will be restless throughout the night and unable to sleep. The Heart houses the Shen (Spirit). After profuse sweating, Yang Qi becomes deficient, leading to insomnia; the Heart governs Blood. After severe purging, Yin Qi becomes weak, also leading to insomnia. In febrile diseases, when pathogenic heat is exuberant, the Shen becomes unclear, causing insomnia. After a new recovery from illness, if Yin Qi has not yet restored, insomnia occurs. If sweating is accompanied by dryness of the nose and inability to sleep, it indicates that the pathogen has entered the exterior.

Wei Qi (Defensive Qi) travels through the Yang meridians during the day and the Yin meridians at night. Traveling through Yang leads to wakefulness; traveling through Yin leads to sleep. Now, those who desire sleep are likely suffering from deficient Yang Qi and abundant Yin Qi, causing their eyes to close and sleep excessively. This indicates that the pathogen has transmitted to the Yin and is no longer in the Yang. However, although excessive sleepiness in Shanghan (Cold Damage) mostly belongs to Shaoyin disease (disease of the Kidney meridian), there are differences. For example, after more than ten days of Taiyang disease (disease of the Bladder and Heart meridians characterized by exterior syndrome), if the pulse is deep and fine, with aversion to cold, curling up, and desire to sleep, this is due to the dimness of Shen Qi. If sweating is accompanied by heaviness of the body, dry nose, delirious speech, blurred vision, and excessive sleepiness, this is Fengwen disease (Wind-Warmth disease). If the lips are black with sores, the throat is dry, the voice is hoarse, and one is taciturn with excessive sleepiness, this is Huhuo disease (a disease characterized by erosion of the mouth, throat, and genitalia). If, after sweating or purging, the pathogenic qi has retreated, the healthy qi has recovered, the body is cool, the pulse is faint, and one snores soundly, this is an auspicious sign.

Aonao (restlessness and discomfort in the chest/epigastrium) refers to a state of inner restlessness and depression, more severe than ordinary irritability. This occurs because the exterior pathogen has not been resolved, but purgatives were hastily used, causing Yang Qi to sink inward into the chest and epigastrium, where it stagnates and fails to disperse. This causes mental disturbance and unease, which may progress to Jie Xiong (Chest Binding, a condition where pathogenic heat and phlegm-fluid bind in the chest/abdomen). If the pathogen is in the chest and epigastrium, vomiting therapy is appropriate; if in the Stomach fu organ, purging is appropriate. After vomiting or purging, if pathogenic qi remains obstructed and uneliminated, causing inner depression and discomfort, treatment should follow the principles of deficiency or excess.

Ju Ji (muscle contraction and tension) refers to difficulty in flexing and extending the hands and feet, resembling a curled-up posture with aversion to wind. Since the four limbs are the root of all Yang meridians, this symptom arises from Yang loss due to excessive sweating, resulting in Yang deficiency.

The tongue is the orifice of the Heart and corresponds to the Fire element of the South; its normal color is red and lustrous. If Shanghan pathogenic heat scorches the body, depleting fluids, the tongue (the sprout of the Heart) becomes dry and shriveled, leading to the formation of tongue coating. If pathogenic heat is in the exterior, white coating forms; if in the interior, prickly coating forms. Whether yellow, black, rough, slippery, prickly, or cracked, these features reflect the depth of heat. Thus, it is said: white and slippery coating indicates gradually deepening pathogenic heat; black and cracked coating indicates extreme pathogenic heat, signaling critical illness. Generally, fresh red and moist tongue is auspicious; dry, rough, and cracked tongue is ominous. There is also a type of Yin-cold syndrome where extreme Water counteracts deficient Fire, presenting with black coating etc., but the coating must be wet, cold, and slippery, not dry or rough, with no thirst or heat sensation, a deep and fine pulse, and cold feet. In such cases, Sini Tang (Decoction for Reversing Collapse) should be used to warm. In summer, patients with black coating suffer from seasonal fire and pathogenic fire burning internally and externally; survival is possible, and death cannot be declared. In winter, black coating indicates certain death. This is the subtle transmission of Heart disease.
For all white coating syndromes, use ginger slices steamed with honey to wipe the tongue. For yellow coating syndromes, use green cloth dipped in mint decoction or cold water to frequently wipe. As for black and cracked coating, it represents Water overcoming Heart Fire. The Classics state: "In febrile diseases, dry mouth and black tongue indicate death."