Summary of Key Points
This article aims to convey that spending prolonged periods in a constantly cooled and comfortable environment created by air conditioning can indeed have subtle effects on both the body and mind. However, these effects are not the traditional "air conditioning illnesses" such as catching a cold or experiencing joint pain immediately after using the AC; rather, they involve more hidden and nuanced physiological and psychological changes.
Detailed Explanation
1. Reduced ability to regulate body temperature
The human body acts like an intelligent "thermostat": it sweats to dissipate heat when hot and shivers to generate heat when cold, with blood vessels contracting or expanding to maintain a constant temperature. However, if one stays in an air-conditioned room with a constant temperature of around 24°C for extended periods, this "thermostat" becomes less efficient over time. For example, stepping outside into the scorching sun at 35°C might cause dizziness or heatstroke, and leaving a warm air-conditioned room in winter might make one feel colder than usual due to slower blood vessel contraction—similar to a machine that has not been used for a while and has lost its efficiency.
2. The respiratory system suffers quietly
If the air conditioner filters are not cleaned regularly, they can accumulate dust, mites, and bacteria, which are then released into the air. Breathing this air over time can irritate the respiratory tract, leading to symptoms such as a dry and itchy throat or occasional coughing. These symptoms are not as obvious as those of a cold but can be persistent and uncomfortable.
3. Slowed metabolism and weight gain
Maintaining a constant body temperature requires energy; for instance, the body burns more fat in winter to stay warm and sweats to dissipate heat in summer. In a constantly cooled environment, the body doesn't need to expend this energy, and if one's diet remains unchanged, excess calories can be stored as fat. This is why many people gain weight while using air conditioning in summer.
4. Mood becomes more stable but less energetic
Changes in temperature affect hormone secretion in the brain. For example, slightly higher temperatures increase dopamine (a mood-enhancing hormone), while lower temperatures increase serotonin (a calming hormone). In a constant-temperature environment, these hormonal fluctuations decrease, leading to feelings of lethargy or lack of energy. For instance, spending a day at home with the AC on might make one feel more tired than going for a walk—because both the body and brain become accustomed to stability and miss the stimulation provided by temperature changes.
5. Weakened immunity
The immune system needs to be exposed to various "threats" (such as slight temperature changes or small amounts of bacteria) to stay strong. Staying in a constant-temperature environment deprives it of this opportunity, making it more susceptible to illnesses when the body encounters external changes (like sudden drops in temperature or exposure to bacteria). In short, the immune system becomes weaker due to a lack of exposure to diverse environmental stimuli.
While these effects are not immediately noticeable as serious illnesses, they can gradually alter one's physical condition over time. Therefore, allowing the body to be exposed to natural temperatures occasionally—such as opening windows in the morning to let in fresh air or going out for some sun on weekends—is actually beneficial for health.