Cortisol is a steroidal hormone responsible for blood glucose regulation, immune functions, and anti-stress responses. It is also an anti-inflammatory and helps regulate blood pressure. Cortisol is made by the adrenal cortex in the adrenal gland which is located on top of the kidneys. Cortisol is released under stressful conditions and is responsible for the 'fight or flight' response when facing a threatening situation. It is also released when blood glucose is too low and helps regulate the glucose levels.
Too much stress can lead to too much exposure to cortisol. Organisms have a relaxation response after cortisol has been released which returns their body to normal. If a person chronically doesn't have enough time to have the relaxation response before another stressor causes more cortisol to release then adverse health effects can occur. Too much cortisol can cause a decrease in bone and muscle tissue, blood glucose problems, an increase in blood pressure, a weakened immune response, and longer healing times.