Cortisol is a hormone produced by the adrenal glands, which are located just above the kidneys. Cortisol affects almost every organ in the body and is important for body functions such as breaking down glycogen and fat for energy, managing stress, and maintaining blood pressure.
Cortisol levels increase when the pituitary gland in the brain releases another hormone called adrenocorticotropic hormone (ACTH). Cortisol levels also rise during times of stress.
WebMD Medical Reference from Healthwise