The common cold is a leading cause of visits to the doctor and absence from work and school.
Outdoor exercise, which keeps our perspiration active and exposes the acupuncture point on the back of the neck to the sun, can help protect adults and children from catching colds.
Thanks to air-conditioning, many people in Hong Kong love to congregate indoors, be it summer or winter. But though this brings short-term comfort, it can also have an adverse impact on our bodies.
We are born with the ability to naturally control body temperature within narrow limits to keep our bodies at an optimum operating temperature, adapting to changes in climate.
For example, sweating is one way to help cool the body by releasing excessive heat from within, while shivering and the constriction of capillaries in our skin and the rising of skin hairs help conserve warmth in the body. However, this temperature control mechanism, monitored by a part of the brain called the thermoregulatory center, is somewhat attenuated in an air-conditioned environment.
Receptors in the brain and skin are less sensitive to external temperature change such as air-conditioning.
This makes us more susceptible to catching a cold when there is a sudden drop in temperature.
In traditional Chinese medicine, exposure to sunlight is a must for our bodies. Sunlight is regarded as one of the sources of yang energy, which provides us with physical power and warmth to prevent the invasion of exogenous pathogens.
The lack of yang energy can cause a person to catch a cold easily. In modern health-care science, there is also growing evidence showing that inadequate exposure to sunlight (ultraviolet radiation and vitamin D) may increase the risk of various autoimmune disease and life-threatening cancers, according to a World Health Organization paper on solar ultraviolet radiation.
The human body can be divided into yin and yang under the Chinese medicine meridian system, a network of energy pathways.
The anterior part of the body belongs to yin and the posterior areas are yang. That is, the yang energy runs well in the meridian on our back.
Keeping our back warm is very important.
There is a famous acupuncture point between the seventh cervical vertebrae and the first thoracic vertebrae, which is commonly used for treating colds and flu - the dazhui point.
Using moxibustion, burning herbs and applying the resulting heat to a specific acupoint, to the dazhui point, is a common practice in healing colds and flu in Chinese medicine.
Children spending most of their time at indoor playgrounds, which are usually held in air-conditioned classrooms with room temperature at only about 22-23 degrees Celsius, may be more prone to catching cold with changes in the weather.
Once kids begin to perspire, some parents often turn on the air-conditioner to lower the temperature. This may numb the kids' natural ability to dissipate the excessive heat via the skin.
Wong Pui-man is a registered Chinese medicine practitioner with a Bachelor of Chinese Medicine degree from the Hong Kong Baptist University. www.facebook.com/ CandyWongAcupuncture