Summer Is Harder to Get Through Than Winter Now

Summer is now harder to get through than winter. It is something I say often in the consulting room.

For winter, better clothing and better heating settled the matter of keeping the body warm. Summer is not like that.

Two seasons inside one day

The difficulty of summer is not that it is hot. It is that the hot, humid outside and the cold, dry air made by the cooling sit inside the same day — a door apart, and sometimes seconds apart.

And summer itself is not the summer it was. In the Korea Meteorological Administration's comparison across 113 years, days of extreme heat rose from 7.7 to 16.9, and tropical nights rose from 6.7 to 28. More than fourfold. It means close to a month of nights that do not cool.

Adjusting to summer takes time

The body does not simply endure heat — it adjusts. Over several days sweat begins earlier and in greater volume, less salt leaves with it, blood volume rises, and the heart beats less for the same work. Much of this happens in the first week.

But this adjustment only settles if a stretch of raised body temperature and sweating comes daily. Spend most of the day inside the cooling and that stimulus never occurs.

It is not that we get through summer unadjusted — it is that we repeat the first day of summer all summer long.

The autonomic nervous system has to coordinate all of it at once

This is why I tell this story.

When the temperature changes, blood pressure follows. When humidity changes, breathing and the body's handling of water change. And a sharp change in the surroundings itself wakes the sympathetic nerves. A small drop in skin temperature is enough to start that response.

These do not run separately. Blood pressure, breathing and body fluid all sit on the same regulating system, so when one is disturbed the others move with it. The body has to settle all of it together — and by the time it has, the opposite environment arrives.

The narrowing and widening of vessels is itself quick. What is slow is the layer beneath it, where blood volume and the sweat glands come round to summer. Only the quick layer keeps being called on; the slow one never takes its place.

What I see in the consulting room

More people now come in the summer with loose bowels, trouble sleeping, and symptoms in the nose and throat.

These three look unrelated, but not entirely. Among the viruses that go about in summer are ones that bring throat and nose symptoms together with an upset stomach. They are a different kind from winter colds. That is why something like a summer cold that also unsettles the gut is not a coincidence.

Sleep is clearer still. Falling asleep and staying asleep lean on the body's inner temperature coming down in the evening, and a hot night blocks that descent. Deep sleep is the most sensitive to heat.

Some of it comes from the cooling. An air conditioner takes moisture out along with the heat. When the nose and throat dry, the defence there thins. That a large gap between indoor and outdoor temperature puts a strain on the body is set out in hospital material too — though what people call summer air-conditioning sickness is not a formal diagnosis but a name for a bundle of symptoms.

One thing I will say plainly: this is not a case for going without the cooling. Enduring the heat is the more dangerous course. The trouble is not the cooling itself but the size of the gap and how often it repeats.

So summer is a season for holding something back

Here my account parts from the usual summer advice.

What people usually hear is to stay cool and drink plenty. I say close to the opposite. It is a season for eating well, holding your strength back, and minding the immune side — the things we have always said about winter.

Eating especially. Appetite drops in the heat, and that is not laziness. Food gives off heat while it is digested. So when body temperature rises even slightly, the body puts a brake on eating by itself. That happens in the hypothalamus.

It does not come of itself — it has to be gone against. That is where "eat well in summer" comes from.

And a body brought round to summer is shaken less

Once the adjustment settles, the same heat moves you less. It is better to let the body meet some heat during the day — a short walk in the cool of morning or evening will do.

Rather than trying to beat summer, I would have you come round to it.

When to see a doctor first

If after being in the heat you feel dizzy or sick and the sweating stops, if a fever will not come down, or if loose bowels run on for days or carry blood — before a story like this, see a doctor first.

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I have gone once around what summer asks of the body. What happens between seasons I have written separately. (The Same Place Gives Way at Every Change of Season)

Korean medicine long set summer down as a season where heat and damp overlap. It did not treat the two as one thing; it separated them, and asked which of the two a given person found harder.

Put into today's terms, one is the work of defending temperature and the other the handling of water and electrolytes. They are different regulations, which is why the harder side differs from person to person.

Physiology is now supplying names for a distinction the old physicians had already drawn. I take those names and turn them back into the patient's own words in the consulting room.

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Sources

• What happens in the body when the gap between indoor and outdoor temperature is large — Asan Medical Center
• A report analysing how days of extreme heat and tropical nights have increased over 113 years — Korea Meteorological Administration, 2024
• A review of how long it takes the body to adjust to heat, and that the stimulus must continue for that state to hold — Sports Medicine, 2018

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