Cortisol is a steroid hormone produced by the adrenal glands, which are located on top of each kidney. Often called the "stress hormone," cortisol is essential for many bodily functions and affects nearly every organ and tissue in the body. It plays a key role in regulating the body's response to stress, but also regulates blood pressure, metabolism, blood sugar levels, reduces inflammation, supports heart function, influences immune responses, controls the sleep/wake cycle, and helps the body use glucose for energy. Cortisol levels typically peak about 30 minutes after waking up in the morning and gradually decline throughout the day, reaching their lowest levels overnight to allow for rest and energy restoration.
The release of cortisol is triggered by various factors, including emotional, psychological, and physical stress (such as illness, injury, or intense exercise), poor sleep, extreme temperatures, and infections. The hypothalamus and pituitary gland in the brain monitor cortisol levels in the blood; if the levels are too low, the brain adjusts hormone production to signal the adrenal glands to fine-tune the amount of cortisol released. Maintaining balanced cortisol levels is crucial for overall health; too much or too little cortisol can lead to health problems. Chronically elevated cortisol levels can suppress the immune system, alter metabolism (potentially leading to diabetes and weight gain), cause osteoporosis and chronic fatigue, and negatively affect brain function and mood. Recent research has also revealed that disrupted cortisol circadian rhythms and increased morning cortisol peaks are closely associated with cognitive impairment. A new method of measuring cortisol levels directly from a blood sample may lead to more accurate diagnoses and treatments for diseases related to cortisol regulation.
