Cortisol is part of steroids, hormones derived from cholesterol. Cortisol is produced in the cortex of the adrenal gland (called the adrenal cortex). Cortisol production is higher in the morning. Cortisol has many functions in the body where it mainly participates in the distribution of fat and regulation of the immune system. It also increases blood glucose levels during periods of stress by transforming fat cells into sugar: the body then has enough energy available to cope with the stressful situation. Drugs are derivatives of cortisol, known as corticosteroids, and are used for their anti-inflammatory properties and decreased immune response.