As summer sets in all we can think about is a nice cold refreshing shower and some cold sweet drink with a fancy straw. This ethereal combination is however a positive feedback loop of even more suffering. How? Let’s start with the idea of homeostasis which is a bodily phenomenon that keeps your metabolism under constant control based on multiple positive and negative feedback loops. Homeostasis is why you sweat when you feel too hot, why you may gain or lose weight, how blood sugar is controlled and many other processes that keep your body within its ideal conditions.
The hypothalamus is the processing center in the brain that controls body temperature. It senses when our body’s temperature falls below 37°C and changes the action of effectors to conserve more heat and vice versa. The effectors may include sweat glands, arteries and veins closest to the skin surface and muscles controlling hair follicles. Heat stroke can happen when the body becomes too hot; and hypothermia when the body becomes too cold.
We have another great article on Body Temperature, you can read it here.
Your body can only stay at a constant temperature if the heat we generate is balanced and equal to the heat we lose. In summer, as a way of dealing with all this heat, our bodies increase production of sweat from sweat glands, open out most of the pores on our skin surface for the heat to escape through and increase blood flow (via vasodilation) to arteries and veins closer to our skin surface so that the heat trapped in our blood may escape as well.
Our bodies respond more to changes in skin temperature than core temperature. So, if we cool part of the body (for instance with a cold sponge, or cold shower), skin blood flow decreases and skin temperature falls.
A cold shower to “cool down” might seem a good choice in that instance. We feel cooler because of the combination of the cold water and the decreased blood flow to the skin, but in fact our core temperature will increase because of reduced heat loss from the body without skin blood flow. Furthermore, the pores on your skin will close in response to the cold temperatures Some minutes later, we feel hotter than we may have before. In contrast, having a warm shower will create a warm sensation on your skin which will kick your heat loss responses into overdrive which will end up cooling your body in the long run.
Hot Cuppa on a Hot Day
Essentially, it’s the same idea as a hot shower but this time your affecting your internal sensors rather than your skin sensors. Hot drinks will increase your core temperature which will also affect your heat release mechanisms and lead to you feeling cooler in the long run.
It is why hot drinks and spicy food are so popular in warmer climates, because they have a quicker reaction on the body and help the consumer get cooler faster and stay cooler for longer.