Estrogen, a steroid hormone, is the primary female sex hormone. Estrogen levels are highest in women of reproductive age and tend to decline following menopause. Melatonin is a hormone produced by the pineal gland in the brain and is involved in the regulation of the body's natural circadian rhythm. Release of melatonin is stimulated by darkness and inhibited by light. Levels of melatonin are often the highest before bedtime.
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The majority of estrogen is produced by the ovaries. Smaller amounts are produced by the corpus luteum, the placenta, the breasts and the adrenal glands. Fat cells also play a role in the maintenance of estrogen levels, and individuals with too little or too much fat deposits may have problems with infertility. A compound known as estradiol is the precursor to estrogen. Estradiol levels are often higher immediately prior to ovulation.
Function of Estrogen
Estrogen levels in women fluctuate and tend the be the highest during a woman's reproductive age. Estrogen is responsible for the development of secondary sex characteristics such as breast development and increases in fat deposits. Estrogen also promotes the development of the uterine lining and helps regulate the menstrual cycle. Additionally, estrogen is involved in the regulation of metabolism, increases in bone formation, protein synthesis, lung function and fluid balance. Estrogen may increase pheomelanin, a pigment found in the skin responsible for pink and red hues.
Estrogen levels rise during puberty. Hormone changes occurring at this time allow for the development of secondary sex characteristics and menstruation in females. Estrogen levels rise naturally during a healthy pregnancy. Abnormally high estrogen levels may be seen in women who are overweight due to increases in fat deposits. Certain tumors and cancers may also increase estrogen levels. Estrogen levels tend to fall during menopause. This drop in estrogen can cause fatigue, hot flashes, moodiness and dryness in the vagina. Low estrogen levels can increase a woman's risk for developing osteoporosis and heart disease.
Melatonin is a naturally occurring compound that is produced by the pineal gland in the brain. Small amounts of melatonin may be produced by bone marrow cells. Once synthesized, the hormone is released into the bloodstream.
Functions of Melatonin
Melatonin is an integral part of the sleep-wake cycle in humans. Melatonin production is stimulated by darkness. This increase causes drowsiness and lowers body temperature. Light suppresses the production and release of melatonin. Therefore, levels are typically low during the day and peak in the middle of the day. Melatonin levels begin to drop during the second half of the night.