For health, our body strives to maintain balance between Yin and Yang (cold/hot). At almost every moment, one or other predominates. For example, if you are talking to a friend, you are displaying more Yang energy than he is. When he talks and you listen, you are more Yin and he is more Yang: you are receptive and he is active. In your own body, your body is either warming you up, for example on a cold day by physical activity or inclining you to wear more or seek a source of external warmth, or to eat something, or shivering. On a hot day cooling you down by perspiring and sending blood to just under your skin.
Warm: in a warm bath, your skin goes pink, you perspire and relax. These show your body doing its best to cool you down. Here it exerts Yin Qi, doing its best to dissipate the heat. You may notice that, save in exceptional situations, after a warm shower or bath lasting more than a few seconds, you will feel less energetic. Your body has to work quite hard to cool you down. That’s why a warm bath before bedtime helps you to become soporific and, from the point of Yin and Yang, it temporarily warms you up, more Yang, but gets your Yin energy going to cool you.
Cold: in cold showers, you shiver, the pores of your skin close up and you tend to contract muscles. Here your body exerts energy (Qi) to keep you warm, specifically Yang Qi. Cold shower researchers examined how people who swam regularly in ice cold water reacted to stress, huge decreases in their uric acid levels. Uric acid levels are often found in people with Kidney disease, obesity and high Blood pressure and gout. When uric acid levels exceed 5.5mls/dL the incidence increases of heart disease and diabetes. These cold swimmers’ uric acid levels became very low. Also, glutathione increased markedly, glutathione being your body’s most powerful antioxidant, used to combat all sorts of stress. When glutathione levels are high, your body’s other antioxidants also remain high.
As much of TICM states, it is important to manage and maintain a balance in your body. Both hot and cold showers/baths are beneficial so long as you are doing what is right for your body during that time period. Sometimes you may need a warm bath before bed, other times a cold shower is just what the TICM doctor ordered.