Autumn in TCM: the season of the Lungs and dryness

My first autumn in Central Europe is filed in memory as a crack in the corner of my mouth.

The building's heating came on in mid-October. Four days later my lips had split, there was a crust in my nose every morning, and my throat felt as though I'd spent the night shouting across a stadium. I assumed I'd caught something. I hadn't. It was the radiator — and a hygrometer that I eventually bought and hung on the bedroom wall.

It read 23%.

The comfortable range for a home is 40–60%. I had been sleeping in a desert and wondering why I woke up flattened.

That was the point at which a line from the Chinese classics stopped being poetry for me. "Autumn creates dryness in Heaven and metal on Earth; in the body it creates the lungs, and on the body's surface, the skin." That is not a metaphor. It is a fairly precise description of what dry air does to a person.

What autumn means in TCM, and why it belongs to the Lungs

In the five-phase system every season gets an element. Autumn gets Metal. Its solid organ is the Lung, its paired hollow organ the Large Intestine. White colour, pungent flavour, west, dusk. Its emotion is grief — and that particular sense of parting that arrives in late October with no external cause whatsoever.

There is one key text here: the Suwen, chapter two, "On Regulating the Spirit According to the Four Seasons." It is roughly 2,200 years old and it issues a direct seasonal instruction rather than a reflection. The three months of autumn are called 容平 — "gathering and levelling." Then, almost verbatim: sleep early, rise early, rise with the rooster; keep the will calm to soften the severity of autumn; gather the spirit inward; do not let your intent scatter outward — and the qi of the Lung will stay clear. And the closing line, which is why the passage was written at all: go against this and you damage the Lung, and in winter there will be nothing left to store.

Note the phrasing. Not "you will fall ill," but "there will be nothing to store." In this logic autumn is not a standalone event. It is preparation. Whatever you gather now is what winter spends.

The seasonal pathogenic factor is 燥, dryness. Of the six classical external factors it is the only one describing not temperature but water. Early autumn, while it is still warm, produces "warm dryness" — a scratchy throat, a dry cough with no phlegm, thirst. Late autumn, closer to frost, produces "cool dryness": chills, congestion, tight skin.

And one more detail that explains half of the autumn complaints people bring to a clinic. In TCM the Lung is called 娇脏, the "delicate organ." It is the only solid organ in direct contact with outside air, so it absorbs the quality of the environment first. It is also credited with governing the skin and body hair: 肺主皮毛. Anatomically that sounds odd — what have lungs to do with skin. In terms of water balance it is exact: both surfaces lose water into the same dry air, simply by different routes.

How it works: air, mucosa, skin

Now the same thing in physiology.

An adult at rest moves somewhere in the region of ten to eleven thousand litres of air through the lungs every day. Before that air reaches the alveoli, the nose and upper airways are obliged to bring it to nearly 37 °C and nearly full saturation with water vapour. Otherwise gas exchange does not work properly. The body does this without asking. The only question is where it sources the water.

It sources it from you. Respiratory water loss at rest runs at roughly 250–400 ml a day. In cold air, under exertion, or at altitude it can reach a litre and a half. This is the water you never see: not sweat, not urine — it simply leaves with each breath.

Then there is the conveyor belt almost nobody thinks about. The airways are lined with ciliated epithelium. The cilia beat at around 12–15 times per second and drive a layer of mucus above them at something like 4–20 mm per minute. That layer traps dust, spores, bacteria and viral particles and carries them out. Mechanical housekeeping, running around the clock.

It runs on one condition: a thin watery layer must remain beneath the mucus so the cilia can move freely. Dry air evaporates precisely that layer. Mucus thickens, cilia begin to slip, transport slows — and this has been measured directly. Nasal mucociliary transport is demonstrably slower when a person breathes dry air than when the air is humidified.

Which leads to a conclusion that is rarely stated out loud. "Everyone gets ill in autumn" is not only about there being more virus around. It is also about the first mechanical line of defence running below its normal speed at exactly that moment.

The skin follows the same arithmetic, more visibly. A healthy stratum corneum holds around 10–15% water. The rate at which that water leaves — transepidermal water loss — depends on the humidity gradient between skin and air. At 40–60% indoors the gradient is moderate. Below 40% the loss accelerates noticeably; below 50% hydration of the stratum corneum drops and micro-cracks appear in the top layer, at which point the barrier starts admitting things it should be keeping out.

And what happens during the heating season? Cold outside air is drawn in and warmed. The absolute amount of moisture in it stays the same; the relative humidity collapses. Typical values in a heated flat with no humidification are 10–20%. My 23% was not even the bad end of the range.

There is a third front, stated plainly in TCM and almost never in everyday advice. The Large Intestine is the Lung's paired organ, and in practice that means the autumn water deficit shows up there too. Hard, dry stools in late October are not a coincidence and not "something you ate."

The classical texts summarised all of this in one sentence: dryness injures the body fluids. Two thousand years before anyone built a hygrometer.

What adjusting for the season actually gives you

Autumn is the one season where nearly everything useful reduces to a single task: hold on to water. That is convenient, because the list of actions is short and the items reinforce each other.

Breathing. Once the mucosa stops drying out, the morning crust in the nose disappears, along with that scrape in the throat on the first swallow of the day. The voice stops sagging by evening — for anyone who talks for a living, that shows up within a week.

Skin. A restored barrier is not about "glow." It is about the absence of tightness after washing and the absence of splits on knuckles and at the corners of the mouth. The barrier, not the quantity of cream applied, decides how skin survives December.

Sleep. Dry night air is a common and almost never suspected cause of waking: the nasopharynx dries, the sleeper switches to mouth breathing, and the rest follows. A hygrometer in the bedroom settles more questions than another tracker will. The mechanics of night-time recovery are covered separately in the sleep quality article.

Immune baseline. Not "boosting immunity" — no such lever exists. The point is that the mechanical barrier and the mucosa work at their normal rate rather than at half speed. How the defence system is actually built is covered in the article on immunity.

And the psychological part, which the classics are not shy about naming as the season's emotion. Autumn is for finishing, not starting. If every October pulls you towards taking stock and feeling melancholy for no reason — you are not broken, you are on schedule.

Who this matters most for — and where it is not enough

The list of people who get the most from an autumn routine is narrow and quite specific.

Anyone spending more than six hours a day in a space with central heating or air conditioning. An office, a flat with old cast-iron radiators, a car with the heater on full — the environment is the same.

People who talk a great deal: teachers, salespeople, anyone who lives in calls. Vocal folds dry first and recover slowest.

Anyone running outdoors in the cold. Under load a person switches to mouth breathing, and the mouth, unlike the nose, barely warms or humidifies incoming air. Respiratory water loss on such a session is several times higher.

People with atopic or allergic skin. For them the barrier is not an abstraction but a daily working question.

People over fifty. Sebum production and sebaceous gland activity decline with age, and the same room humidity is tolerated distinctly less well at fifty-five than at thirty.

Now the honest part — where none of the above is sufficient.

An autumn routine is background, not a medical intervention. It replaces nothing that has been prescribed. If you have asthma or COPD, a humidifier is useful and has precisely nothing to do with your inhaler or your treatment plan. A cough lasting longer than three weeks, coughing blood, fever, breathlessness at rest, chest pain — none of that is "seasonal dryness." That is a reason to see a doctor, and sooner is better than in a month's time. Unexplained weight loss and night sweats alongside a cough, more so.

And a word on supplements, so there are no illusions. Adaptogens such as lingzhi work cumulatively and over the horizon of a course, with regular use. They support the body's resilience to load — and they do nothing in three days. Expect the response profile of a painkiller and disappointment is guaranteed.

How to apply it: eight weeks of an autumn routine

Not fifteen points. A short set you can actually hold until the end of November.

First — measure. A hygrometer is cheap and it turns "it feels dry" into a number. Hang it in the bedroom, read it in the morning. Target: 40–60%.

Second — raise the humidity. A humidifier if you have one; a wet towel on the radiator and a bowl of water if you don't. The detail people forget: humidifiers need cleaning. Regularly and properly, otherwise you have built a microbe atomiser rather than a helper.

Third — drink warm, not iced. In TCM logic, cold water in autumn dampens an already weakened "middle fire." In everyday logic, warm drinks simply get drunk more often and in greater volume. Both explanations point the same way.

Fourth — white foods. The classical autumn list: pear, lily bulb, snow fungus, lotus root, almond, honey, sweet potato and Chinese yam. The simplest recipe of the lot is a pear steamed or baked with a spoonful of honey. It works as gentle internal moistening and takes fifteen minutes.

Fifth — remove what dries. Large quantities of chilli, spirits, the fourth coffee of the day. In autumn their price is higher than it is in June.

Sixth — the Suwen sleep schedule, translated into 2026. Go to bed 30–40 minutes earlier than your summer time, get up with the light. Keep the bedtime window inside half an hour — consistency matters more than the hour itself.

Seventh — breathe through the nose. Twenty to thirty minutes of walking a day, nasal breathing even when the mouth is tempting. The nose is the only built-in humidifier you already own, and it is free.

Eighth — skin. The three-minute rule: apply your moisturiser to still-damp skin within three minutes of the shower, before the water has gone. Shorter showers, cooler water. Gel or serum as the first layer, oil as the second — oil adds no water of its own, it seals in what is already there.

Ninth — a supporting course, if you use one at all. Lingzhi is chosen more often than other adaptogens in autumn precisely because of its association with the Metal season. The unit of measurement here is weeks, not days.

And the general rule for judging any of it: change one item at a time, allow 4–8 weeks, and write three lines each evening — sleep, energy out of ten, state of throat and skin. In two months you will have your own dataset instead of a vague sense of "a bit better."

Conclusion

Autumn dryness is the most underrated everyday problem I know of. Nobody counts it as a problem, because it does not hurt. It simply removes water from the body through three channels at once — breath, skin, gut — quietly, for eight weeks, until the central heating comes on and it gets worse.

The old texts called this the season of Metal, of the Lung, and of dryness, and prescribed gathering rather than spending. A hygrometer says exactly the same thing, only in numbers.

My own conclusion, after several northern winters: in autumn the thing to change is not your supplement stack but two environmental parameters — bedroom humidity and bedtime. Everything else is only worth doing on top of those.

Buy a hygrometer. It costs less than any cream and is more honest than any article, including this one.