Surviving the Air Conditioning Hell of Midsummer! 10 Tips to Avoid Catching a Cold Even When It's Scorching Outside and Freezing Inside

2025年07月02日 16:50

1. Introduction──The Real Culprit of "Summer Colds" is Temperature Differences

In urban areas of Japan, the number of midsummer days (with maximum temperatures of 30°C or higher) is increasing year by year, expanding the temperature difference between outdoor and indoor environments. The autonomic nervous system, responsible for regulating human body temperature, struggles with sudden changes of 5°C or more, leading to decreased immunity due to repeated cooling and sweating. This is particularly noticeable in women and those with a predisposition to cold sensitivity, as peripheral blood flow tends to decrease, resulting in symptoms of air conditioning sickness such as headaches, menstrual irregularities, and indigestion.med.or.jp

2. Symptoms and Mechanisms of Air Conditioning Sickness

Autonomic Nervous System Imbalance: Prolonged sympathetic dominance leads to blood vessel constriction → coldness, decreased gastrointestinal function.
Disruption of Surface Body Temperature: A "dual structure" where the head sweats while the feet are cold, causing blood flow disorders.
Dryness Stress: Dehumidification by air conditioning dries out mucous membranes, increasing the risk of viral invasion.
According to medical association data, 26% of women working in environments with a room temperature of 20°C and humidity below 40% report symptoms of summer colds.med.or.jp

3. The 5°C Temperature Difference Rule──Environmental Settings for Home and Office

Recommended Setting: Keep the difference from outdoor temperature within 5°C (or a maximum of 7°C if difficult).
Use of Circulators: Circulate cool air near the ceiling to lower the perceived temperature.
Ventilation + CO₂ Sensors: The Ministry of Health, Labour and Welfare recommends keeping CO₂ levels below 1,000 ppm, and visualizing both CO₂ and temperature can prevent overcooling.mhlw.go.jpwbgt.env.go.jp

4. Humidity of 50-60% is the Crossroad of "Comfort and Health"

When humidity falls below 50%, mucous membrane dryness progresses and virus activity increases, while exceeding 60% raises concerns about mold and mite proliferation. Use air conditioners with humidifying functions or partially adjust humidity with wet towels and desktop fans. As the Wet Bulb Globe Temperature (WBGT) rises with higher humidity, indoor adjustments are key when going out.wbgt.env.go.jp

5. "Portable Insulation Layer"──Layering Techniques to Block Cold Air

According to VOGUE JAPAN's 2025 light outerwear feature, long-sleeve shirts and lightweight cardigans with breathability are ideal for air conditioning and UV protection. Keep foldable linen jackets and large stoles in your bag to keep your neck, shoulders, and knees warm, preventing a drop in core temperature.vogue.co.jp

6. "Air Conditioning from the Inside" with Warm Meals

Consuming only cold food and drinks diverts blood flow from the stomach and intestines, reducing digestive enzyme activity. From a Chinese medicine perspective, the "yang energy of the spleen and stomach" is compromised,

Morning: Miso soup + ginger porridge
Lunch: Ginger pork set meal with room temperature tea
Dinner: Sesame and ginger soy milk hot pot

Warming the internal organs with warm ingredients is highly effective.kracie.co.jp

7. Recommendation for "Warm-Cold Hybrid" Drinks

Immediately after going out, replenish electrolytes with room temperature sports drinks, and reset your internal organs with warm water or hot barley tea once indoors. Alternating between warm and cold helps control sweating and aids in body temperature regulation.

8. Balance the Autonomic Nervous System with Baths and Stretching

Soaking in water around 40°C for 10 minutes promotes parasympathetic dominance, improving sleep onset. Performing a one-minute forward bend stretch after bathing gradually lowers core body temperature, leading to quality sleep.

9. Protect Immunity with 7 Hours of Sleep

A U.S. study reports that people who sleep less than 6 hours have about a 40% higher risk of catching a cold compared to those who sleep 7 hours or more. Adjusting the air conditioning timer and airflow direction to ensure deep sleep in the first 90 minutes of sleep promotes the proliferation of immune cells.

10. Conclusion──Simultaneously Implement the "Five Pillars"

5°C Temperature Difference
Humidity 50-60%
Keep Outerwear Handy
Warm Meals + Warm-Cold Drinks
Bathing & 7 Hours of Sleep
If you make these a routine, neither air conditioning sickness nor summer colds will be a concern. Start implementing them today to comfortably get through the scorching summer.

🔍 List of Reference Articles (with Links)

← Back to Article List

Cookie Usage