Autumn Dryness Is Not a Shortage of Water

Wildfires come in autumn not because the sparks grow stronger. It is because what burns has dried out. The same spark spreads in a dry wood and goes out in a wet one.

Something similar happens in the body in autumn. As the air dries, skin and mucous membranes dry first. But "drying" in the body looks rather different from the picture we usually have of it.

What I hear in the clinic is not "it feels dry"

These are the words I hear often in autumn.

• The mouth feels dry, but the saliva is sticky
• The eyes have thick discharge in the morning
• The nasal mucus is clear, but too tacky to come out
• The nose is blocked, yet nothing runs

If this were a shortage of water, the amount would simply fall. What people actually experience is the amount falling while the character changes. What was thin turns thick.

This is what drying in the body actually looks like.

Under tension, saliva turns thick

The salivary glands take instruction from two branches of nerve together. When the branch that works at ease is on, thin saliva comes in plenty. When the branch that works under tension is on, a smaller, protein-rich, thicker saliva comes instead. That same branch also narrows the vessels supplying the mucosa.

That is why the mouth goes bone dry under tension. Not because water is short in the body, but because the character of the secretion has changed in that moment.

In autumn these things overlap. The air is dry, and the widening gap between day and night temperatures tips the body toward tension. It dries from outside while sending out less from within.

Several other roads lead to the same place. Secretion falls with age; it falls with fever or dehydration; and severe dieting reduces body fluid outright.

Thickened mucus does not get swept away

The lining of the nose and airways is densely set with fine hairs that drive mucus in one direction. Dust and bacteria stick to that mucus and ride out with it. This work is called mucociliary clearance.

It only works while the mucus stays suitably thin. Once mucus thickens, the hairs cannot push it and it clings where it is. What should have been carried out stays put.

This is part of why colds and rhinitis rise in autumn. The viruses have not suddenly turned fierce; the sweeping is not getting done. The dry wood returns here.

So drinking a great deal of water does not, by itself, resolve much. Water taken in does not go straight to thinning the mucus on the surface. If the moisture evaporates and only the tacky part remains, it congeals further. What matters alongside the water you drink is the humidity that stays around you and the secretion itself.

Older medicine aimed at this same place

Korean medicine has long used herbs aimed at dried mucosa. Of ginseng it said saengjin-jigal (生津止渴) — it generates fluid and stops thirst. Put into today's terms, that points toward improving secretory function and restoring the sheen of the mucosa.

The direction is not to pour water in from outside but to have the body send it out itself. When I explain this distinction to patients, I tend to reach for a glass of water and a tap. What the old phrase pointed at, and what we now understand about the control of secretion, are looking at the same place.

Drying is not confined to the surface

To read dryness as an affair of skin and mucosa alone is to see half of it. The matrix within the tissues holds water too. How much water collagen and the substances filling the spaces between it can hold decides whether tissue stays supple or turns stiff.

Some people say their body feels stiffer in autumn, and this is not unrelated. That side does not answer to drinking water; it eases with slow, low pressure, or with a rise in temperature. It is why a warm bath and unhurried stretching help.

So in practice

When I hear of drying, I first separate whether the amount fell or the character changed. If it has turned thick, I look less at increasing water and more at why secretion has fallen.

I ask about sleep, about whether tension has been running on, about how dry the rooms are. I also ask how the summer went — a body worn by heat dries more easily in autumn. (Summer Is Now Harder to Get Through Than Winter) In autumn, adjusting the humidity of the bedroom alone changes the morning symptoms for some people.

When to be seen first

If dry mouth persists regardless of season, or the eyes dry severely along with it, the salivary and tear glands themselves may be involved and examination comes first. A fair number of medicines cause dry mouth, so please tell me anything you are taking.

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Korean medicine did not read dryness as a simple shortage of water. The old phrase attached to ginseng, saengjin jigal, says as much: not pour water in, but let the body bring it forth itself.

It was only after seeing patients whose mouths stayed sticky no matter how much they drank that I understood why the old phrase was worded the way it was.

Sprinkling water on a dry forest and letting the forest hold water itself are different things. The old prescriptions aimed at the second, and physiology is now putting names to that place.

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Sources

• A review of how the nerve branch that works at ease yields thin saliva while the branch that works under tension yields thicker, protein-rich secretion and narrows the vessels — Physiological Reviews, 2022
• A review of how the hydration of mucus governs whether cilia can clear it, and how dried mucus adheres instead of being swept away — American Journal of Respiratory Cell and Molecular Biology, 2006

Written by Dr. Heo Ji-young (Ph.D. in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)