What should I eat when I can’t sleep?

Most people asking this want a food to add. The tradition’s first answer is about the meal you already eat. If supper is large, late or cold, no bowl of anything afterwards will undo it; the stomach will still be working when you lie down, and the Suwen’s line about that is two thousand years old and still true. So: the evening meal smaller than lunch, finished three hours before bed, and warm. Do that for a fortnight before adding anything.

Then, and only then, the kitchen has a short list, and which end of it you reach for depends on which kind of sleeplessness you have. The person who lies awake hot, dry-mouthed and sharp is given cooling, settling foods. The person who sleeps thinly, dreams all night and wakes tired is given building ones. Those are nearly opposite lists, and this is the one place the tradition insists on knowing which you are.

The Suwen makes the link between the stomach and the night in a chapter on counterflow, where qi is running the wrong way. It is quoted in every later book on sleep, and it is the reason a Chinese physician asks what you ate before asking what you took.

The kitchen half of the tradition is the materia medica, and the entry it reaches for first at night is the lotus seed. Li Shizhen’s account of it in 1596 uses the phrase the whole sleep tradition uses: joining the heart, which is high and hot, with the kidney, which is low and cool.

Three kinds of sleeplessness, three shelves in the kitchen. The tongue usually says which shelf.

The four foods the tradition has kept on the table for the night, and how they are usually taken. They are foods, not medicines, and they are slow.

• Lotus seed 莲子: a small handful, soaked, simmered with rice into a soft congee, eaten as the last thing three hours before bed. Leave the bitter green heart in if you run hot; take it out if you run cold.
• Jujube 大枣: three or four, split, simmered in water for twenty minutes and drunk warm in the evening. The Shennong Bencao Jing says it calms the middle and nourishes the spleen.
• Goji 枸杞: a spoonful added to the jujube water, for the tired-and-light picture, and for anyone who has spent the day looking at a screen.
• Reishi 灵芝: sliced and simmered for an hour, drunk as a bitter tea in the early evening, for the mind that will not stop circling.

What to leave out matters as much. Alcohol puts you under and wakes you at three. Coffee and strong tea after noon are still in the body at eleven. Sugar late in the evening is the commonest cause of the heavy-and-full night we see. And ginger, which the tradition loves in the morning, is a warming, rising food and belongs nowhere near bed.

• Supper smaller than lunch, warm, and finished three hours before bed.
• One warm drink from the list above in the evening, not three; the tradition is wary of drinking much late, for the plain reason that you will be up.
• The same rising hour every day. Food helps at the edges; the rising hour holds the middle.
• Warm feet before bed, a basin of hot water for ten minutes, especially for the hot-and-wakeful.

None of that is a promise, and we make none. The kitchen is slow, and it works at the edge of a night already well laid.