For women in spontaneous labor, contractions are usually two to five minutes apart, last from 30 to 60 seconds, and have moderate strength. The easiest way to assess the power of labor is to time the frequency and duration of the contractions (from the beginning of one to the beginning of the next).
Melatonin, hormone secreted by the pineal gland, a tiny endocrine gland situated at the centre of the brain. Melatonin was first isolated in 1958 by American physician Aaron B. Lerner and his colleagues at Yale University School of Medicine.
Both cortisol and adrenaline are released in response to stress. Cortisol production is regulated by the pituitary gland. This is a small gland behind the nose and under the brain. The pituitary gland releases adrenocorticotropic hormone (ACTH). This is a hormone that causes the adrenal glands to release cortisol. Adrenaline production is regulated by nerves coming from the brain and spinal cord and by circulating hormones.