When you’re physically or emotionally stressed, your body snaps into fight-or-flight mode. Cortisol rushes through your system, signaling your body to release glucose. Glucose, in turn, provides energy to your muscles so you are better prepared to fight off a threat or run away. During this cortisol rush, your heart rate may rise, your breathing may become rapid, and you may feel dizzy or nauseated.

https://www.cnn.com/2023/03/31/health/exercises-to-reduce-stress-wellness/index.html