Japanese Advised to Avoid Risk of Heatstroke with Pre-Summer Acclimatization

Japan Data

Health
Lifestyle
Disaster

May 26, 2025

The soaring temperatures of summer are on the way in Japan, where there is growing interest in “heat acclimatization” or getting the body used to hot weather through exercise or baths in order to ensure it can sweat properly before high summer kicks in.

When people move, their body temperature rises, at which point their body will produce sweat or increase their skin temperature to release heat and cool them down. However, if that function is not working properly, they will keep getting hotter and start to feel physically unwell, which in severe cases can lead to heatstroke.

In a survey conducted by Daikin Industries, aimed at 300 people aged 20 or over from each of Japan’s 47 prefectures (14,100 respondents in total), 64.6% stated that they had experienced some form of “heatstroke symptoms” last summer, including either being diagnosed with heatstroke at a hospital, feeling that they had symptoms, or feeling otherwise unwell.

At 51.4%, the most common physical issue respondents experienced due to heatstroke symptoms was “reduced quality of sleep,” followed by 46.0% “being constantly tired” and 30.8% “feeling weak and lethargic.”

Even if these symptoms are not severe enough to be diagnosed as heatstroke, they can lead to decreased performance in work or study, and although appearing mild at first, can worsen if left untreated.

As well as keeping the room cool and wearing breathable clothes, an effective way to avoid heatstroke is to acclimatize before the real heat of summer kicks in by walking, jogging, doing strength training, stretching, and bathing to make sure your body can sweat more easily.

When asked about “heat acclimatization,” just 7.7% of respondents had a good knowledge of what it was and even when including those who had at least heard of the term, the total was only around 30%. Daikin Industries advised that “in the same way you do a test run of your air-conditioning unit before the start of summer, you need to prepare your body as well so that it can sweat.”

(Translated from Japanese. Banner photo © Pixta.)

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