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