Cortisol, a stress hormone, causes many reactions in your body: faster breathing, pounding heart, sweats, clammy hands, stomach aches, etc.

1. Breathing is more rapid and irregular. Why? So that your muscles get enough oxygen to fight the threat.
2. Your heart is beating fast. Why? The body makes the blood circulate faster to increase the oxygen going to the muscles and the brain.
3. You have a stomach ache, a dry mouth or feel like vomiting. Why? Because this isn’t the time for your body to digest but to fight the mammoth (stress), so it is on pause. The body stops digesting so that this energy can be used to fight the enemy.
4. You are hot or sweating. Why? Because when you are stressed, the body and brain generate more heat, the same way as when you participate in a sport that takes lots of energy. You sweat so that you don’t overheat.
5. You are shaking, your muscles are tense. Why? All the energy stored in the body by stress is in your muscles; all this blood and oxygen prepares your muscles for the fight. This causes tension in your body. So, for example, your hands can tremble, your fists tighten or your jaw clench. You will also see that this makes you much stronger.
6. Your vision is better. Why? Because, when you feel stress, your pupils dilate (letting more light into your eyes) so that, to help you survive the threat, you can see better in the dark when necessary.
7. You start to quickly look from place to place. Why? Because you are analysing your surroundings to see if there are any other dangers and also because you are looking for clues that will end the threat.
8. The hair on your body stand up. Why? Think about a cat that finds itself stressed by a dog. Its fur will stand up to make it look bigger and scare its enemy. It’s the same thing for human beings, although we have much less hair than our prehistoric ancestors.
9. You become more irritable and get angry spontaneously. Why? If something distracts you while you are analysing your surroundings to find clues that will stop the threat, you risk reacting with spontaneous anger.
10. You constantly think about the situation that stresses you. The brain’s role being to ensure survival, it won’t be able to concentrate on something other than the threat until the threat has been overcome. It’s the little hamster inside your head, you know?
11. You begin to forget things. Since your brain can’t take its attention away from the threat that is disturbing it, it becomes more and more difficult for you to remember other information in your surroundings that aren’t directly related to the threat.

You can therefore feel bad when you are stressed because your body is reacting to the threat, whether it is real or not. It acts this way to be more alert to face the dangers and to adapt so that your reactions are effective.

Reference:

Sonia Lupien, sonialupien.com