During stress, the body produces a hormone called cortisol, which prepares it for threats. As a result, you may experience shortness of breath, headache, nausea, muscle tension, and increased heart rate. The hormone also reduces insulin production and narrows the arteries. Your body can tolerate these changes for a short time. However, if the stress does not reduce, the effect of cortisol on the body may lead to cardiovascular diseases, diabetes, irritable bowel syndrome, and other health conditions (8).