Why does my skin itch at night?

The tradition has a word for anything that moves about the body and changes quickly, and the word is wind. Itch is wind’s signature: it comes and goes, it moves from place to place, it is worse when the body is warm and still. And the tradition has an explanation for why wind is worse at night, which is that the defensive qi, the layer that patrols the surface by day, goes inward after dark. Whatever was on the skin, heat, damp or dryness, has the surface to itself until dawn.

Which of those three it is decides everything else. The hot itch is red, warm to the touch and worse after wine, spice and the warmth of the bed. The damp itch weeps and blisters and is worse in wet weather. The dry itch is the fine, scaly, maddening itch of skin that has too little blood to moisten it, worse in winter and after a hot bath, and it belongs to the old and the tired. Under all three are the plain causes: a hot bedroom, wool, a scalding shower before bed, and dry heated air.

The Lingshu gives the timing in a chapter that divides one day into the four seasons. It is written about illness in general, and it is the reason every night complaint in the tradition, itch, cough, pain, fever, is read as the body’s guard having gone in.

The Suwen gives the character of wind, and, in the chapter that lists what belongs to what, gives itch to the heart, which is the tradition’s way of saying that itch is a matter of heat and of the blood. The Ming manuals of the skin, the Yizong Jinjian of 1742 above all, added the third picture: blood too thin to moisten the surface, so that it dries and wind rises from the dryness.

Three pictures. The look of the skin and the tongue usually decide, and they are given opposite advice.

• A warm bath, not a hot one, and not straight before bed. Heat opens the surface, and the itch follows it in.
• Oil the skin after the bath, while it is still damp. Sesame oil is the classical choice; any plain oil does. The dry-and-old picture is half answered by this alone.
• A cool bedroom, cotton on the bed and on the body, and no wool against the skin.
• No alcohol, spice, lamb or prawns in the evening for the hot-and-red picture; the tradition calls these the foods that raise, 发物.
• Nails short. A cool, damp cloth on the place for the hot itch instead of the nails.
• A washing powder without scent, and the sheets rinsed twice. The plain causes are plain.

None of that is a promise, and we make none. It is the floor.

• Mulberry leaf 桑叶, steeped as a tea in the afternoon, for the hot-and-red: the Shennong Bencao Jing gives it to cold and heat on the surface.
• Chrysanthemum 菊花 in the same cup, for the hot-and-red and for anyone whose itch comes with a hot head.
• Job’s tears 薏苡仁 in a morning congee, for the damp-and-weeping, with less sweet and less dairy.
• Goji 枸杞 and jujube 大枣, simmered together, for the dry-and-old: the tradition’s plainest way of building the blood that moistens the skin.
• Nothing warming for the hot picture: no ginger, no cinnamon, no lamb, no wine.

On the back of the hand, in the web between thumb and forefinger, is Hegu, Large Intestine 4, 合谷, the Joining Valley: the point the old rhymes give to the face and the surface. Thumb pressure, a minute each side, in the evening. It is avoided in pregnancy, and we mean that; use nothing on this page but the bath and the oil if you are or might be.