As we know, the pace of modern life is very intense. People are busy with their work, activities and entertainment during the day. Therefore, they like to wash their hair at night when they are free.
Of course, it’s fine if you give your hair enough time to dry when you wash your hair at night. But sometimes you are too busy to wash your hair before 10 pm and feel so tired after washing that you always go straight to bed and sleep before the hair is completely dry. To do so, the elders will say that it will give you a headache later. In fact, his words are somewhat reasonable through modern scientific research.
We should know that the human body always produces heat continuously in the process of metabolism to maintain body temperature. And the heat would be transferred to the surface layer of the organism through blood circulation and would be emanated to the outside by forms of radiation, conduction, convection and evaporation.
For those with strong body resistance and normal regulation function, the two processes of heating and cooling are in balance, that is, the heat will increase when the body temperature decreases, causing the body temperature to remain around 37 C. But for people who have weak body resistance and poor body temperature regulation function, they are easy to get cold by full or local exposure to cold.
After washing the hair with warm water, the capillaries of the scalp will dilate due to the warming effect and the body heat radiating around will increase. Meanwhile, wet hair will cause a lot of water to evaporate, which takes a lot of heat out of it. Generally speaking, 500 calories will be lost when one gram of water evaporates.
As heat loss increases and the body cools, upper airway capillaries reflexively shrink, partial blood flow volume is reduced, and upper airway resistance decreases, leading to existing viruses or bacteria have a chance to intervene. , grow and reproduce. It will result in respiratory tract infections, which make people have flu-like symptoms such as a runny nose, nasal congestion, headache, or fever.
In general, you should avoid washing your hair before bed. Even if you had to do that, you should towel dry your hair. This way you won’t catch a cold.