阴阳易者，如换易之易，以其邪毒之气而交相易换也。男子病新瘥，妇人与之交，动淫欲而反
得病者，妇人病新瘥，男子与之交，动淫欲而反得病者，其候身重气乏，小便绞痛，头不能举，足不
能移，四肢拘急，百节解散，眼中生花，热气冲
胸。在男子则阴肿，入小腹攻刺；在妇人则里急连腰，胯重引腹内痛。若手足挛拳，其脉离经者，
皆不治也。其不因易而自病复发，为之女劳复，通用逍遥散之加减治也。
不得眠者，阳盛阴虚，则昼夜不得眠。盖夜以阴为主，阴气盛，则目闭而卧安。若为阳所胜，
故终夜烦扰而不得宁，所谓阴虚则与夜争也。汗出鼻干，不得卧者，邪在表，干葛解肌汤。若胃有
燥屎，大热错语，及大汗，胃中干，不得眠者，邪在里也，用大承气下之。胃不和则卧不安，故宜
彻热和胃也。若汗下后虚烦不得眠，栀子豉汤。咳而呕，心烦闷不眠者，水气也，猪苓汤。下后复
热，昼日烦躁，夜则安静，无大热者，干姜附子汤。吐下后心中懊 不眠者，栀子豉汤。阳胜阴，
狂言不眠，乱梦，心烦乏气者，酸枣汤。阴胜阳，则惊悸昏沉，大热干呕，错语呻吟，不眠者，犀
角地黄汤治之。汗出，脉虚不眠者，小建中汤主也。
夫卫气者，昼则行阳，夜则行阴。行阳则寤，行阴则寐。阳气虚，阴气盛，则
目瞑，故多眠，乃邪传于阴而不在阳也。昏昏闭目者，阴自阖也。默默不言者，阴至静也。太阳病
十余日，脉浮细，嗜卧者，外已解，神将复也。设胸满胁痛，鼻干，不得汗，嗜眠者，风热内攻，
不干乎表，故热气伏于里，则喜睡。不得汗者，小柴胡汤。脉浮者，羌活冲和汤，冬用麻黄汤。少
阴病，但欲寐，尺寸俱沉细者，四逆汤。少阴病，欲吐不吐，欲呕不呕，心烦多寐，五六日，自利
而渴，小便白者，四逆汤；若复烦热不得卧者，不治。三阳合病，欲眠，目合则汗，谵语者，则有
热也，小柴胡汤。其胃热者，亦卧也，犀角解毒汤。风温、狐惑亦有此证，开在后条。
Yin-Yang Exchange (Yin Yang Yi), referring to the "exchange" as in swapping, denotes the mutual exchange of pathogenic toxic qi. If a man, newly recovered from illness, engages in sexual intercourse with a woman and falls ill again due to sexual arousal; or if a woman, newly recovered, engages in sexual intercourse with a man and falls ill again due to sexual arousal, the symptoms include heavy body, lack of qi, painful cramping in urination, inability to lift the head, inability to move the feet, spasm and tightness of the four limbs, dissolution of all joints, visual hallucinations (seeing flowers), and hot qi rushing to the chest. In men, it presents as swelling of the genitals with stabbing pain radiating to the lower abdomen; in women, it presents as abdominal urgency extending to the waist, heaviness in the hips pulling into internal abdominal pain. If there is curling of the hands and feet into fists, and the pulse deviates from the normal meridian pattern, these are all considered untreatable. If the disease recurs spontaneously without sexual contact, it is called "Female Labor Recurrence" (Nü Lao Fu), generally treated with modified Xiao Yao San (Free and Easy Wanderer Decoction).
Insomnia: If Yang is excessive and Yin is deficient, sleeplessness occurs day and night. Night belongs to Yin; when Yin qi is abundant, the eyes close and sleep is peaceful. If overcome by Yang, restlessness persists throughout the night, described as Yin deficiency competing with the night. If accompanied by sweating, dry nose, and inability to lie down, the pathogen is in the Exterior; Gan Ge Jie Ji Tang (Pueraria Decoction to Resolve the Muscle Layer) is indicated. If there are dry feces in the stomach, high fever with delirious speech, profuse sweating leading to dryness in the stomach, and insomnia, the pathogen is in the Interior; Da Cheng Qi Tang (Major Order the Qi Decoction) should be used to purge. When the Stomach is not harmonious, sleep is unsettled, so clearing heat and harmonizing the Stomach is appropriate. After sweating or purging, if vexation and insomnia occur due to deficiency, Zhi Zi Chi Tang (Gardenia and Fermented Soybean Decoction) is indicated. If coughing and vomiting accompany irritability and insomnia, it is caused by Water-Qi; Zhu Ling Tang (Polyporus Decoction) is used. After purging, if fever returns with daytime irritability but nighttime quietness, and no high fever, Gan Jiang Fu Zi Tang (Dried Ginger and Aconite Decoction) is used. After vomiting or purging, if mental restlessness and insomnia occur, Zhi Zi Chi Tang is used. If Yang overcomes Yin, causing delirium, insomnia, chaotic dreams, irritability, and qi deficiency, Suan Zao Ren Tang (Sour Jujube Seed Decoction) is used. If Yin overcomes Yang, causing palpitations, drowsiness, high fever, dry retching, delirium, groaning, and insomnia, Xi Jiao Di Huang Tang (Rhinoceros Horn and Rehmannia Decoction) is used. If sweating and a deficient pulse accompany insomnia, Xiao Jian Zhong Tang (Minor Construct the Middle Decoction) is the primary treatment.
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. If Yang qi is deficient and Yin qi is abundant, the eyes close, resulting in hypersomnia. This indicates the pathogen has transmitted to Yin and is not in Yang. Drowsiness with closed eyes reflects the natural closure of Yin. Silence reflects the stillness of Yin. In Taiyang Disease lasting more than ten days, if the pulse is floating and fine, and the patient desires to lie down, the exterior pathogen has resolved, and the Shen (Spirit) is recovering. However, if there is chest fullness, hypochondriac pain, dry nose, anhidrosis, and hypersomnia, wind-heat is attacking internally, not involving the Exterior. Thus, hot qi is latent in the Interior, leading to a preference for sleep. For anhidrosis, Xiao Chai Hu Tang (Minor Bupleurum Decoction) is used. If the pulse is floating, Qiang Huo Chong He Tang (Notopterygium Decoction for Harmony) is used; in winter, Ma Huang Tang (Ephedra Decoction) is used. In Shaoyin Disease, if the patient only desires sleep, and the Cun, Guan, and Chi pulses are all deep and fine, Si Ni Tang (Four Reversal Decoction) is used. In Shaoyin Disease, if the patient wants to vomit but cannot, feels irritable and sleeps much, after five or six days, has spontaneous diarrhea, thirst, and white urine, Si Ni Tang is used; if followed by irritability, heat, and inability to lie down, it is untreatable. In Combined Disease of the Three Yang, if the patient desires sleep, sweats upon closing the eyes, and speaks deliriously, it indicates Heat; Xiao Chai Hu Tang is used. If the cause is Stomach Heat, hypersomnia also occurs; Xi Jiao Jie Du Tang (Rhinoceros Horn Detoxification Decoction) is used. Feng Wen (Wind-Warmth) and Hu Huo (Fox-Hu Syndrome) may also present this syndrome, detailed in subsequent sections.