Cortisol is the main hormone that regulates stress. It regulates the fluid balance and blood pressure and shuts down unnecessary functions of the body so that all our energy can focus on the threat.

But there are a few other hormones that play a role too.

1. Adrenaline: You must have heard the phrase 'adrenaline rush'. This hormone provides the boost of energy we get when a threat appears.

2. Norepinephrine: This hormone is similar to adrenaline. Its main purpose is to increase our focus and alertness.