Human Hormones

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a hormone found in the human body. It is secreted from enterochromaffin cells in the gastrointestinal tract and the serotonergic neurons in the brain. Serotonin is classified as an amine hormone.
Secretion and Production

Serotonin is produced in and secreted from the enterochromaffin cells in the gastrointestinal tract. It is synthesized from the amino acid tryptophan. After production, serotonin is secreted into the blood stream.

Serotonin has many effects on the human body. It is believed to play an important role in the regulation of mood, sleep, vomiting, sexuality, and appetite. Serotonin has been thought to play a part in many disorders, notably as part of the biochemistry of depression, migraine, bipolar disorder, and anxiety. Recent research suggests that serotonin also plays an important role in liver regeneration. Additionally, it induces cell division throughout the body.
Pharmacological Uses

Synthetic serotonin has several common uses:

Psychological Disorders
Low levels of serotonin are commonly associated with many different psychological disorders. Synthetic serotonin is commonly used to raise serotonin levels in people suffering with depression, anxiety, bipolar disorder, obsessive-compulsive disorder, and seasonal affective disorder. Additionally, it is commonly used to treat obesity caused by depression and poor impulse control.

Pre-Menstrual Syndrome
Serotonin is commonly used to treat symptoms associated with PMS, including moodiness, food cravings, and irritability.

Eating Disorders
Synthetic serotonin is commonly used to treat eating disorders that are caused by both depression and poor impulse control, most commonly bulimia and binge eating.

Migraine
Studies have shown that migraine headaches are associated with low serotonin levels. Therefore, some people with migraines are treated with synthetic serotonin.

Insomnia
Insomnia is also associated with low levels of serotonin. Synthetic serotonin has been shown to promote sleep in some people who suffer with insomnia.

Melatonin, also known as 5-methoxy-N-acetyltryptamine, is a hormone found in the human body. It is secreted by the pineal gland in the brain. Melatonin is classified as an anime hormone; its chemical formula is C13H16N2O2.
Secretion and Production

Melatonin is produced in and secreted from the pineal gland in the brain. It is synthesized when Tryptophan is derived from serotonin. Tryptophan is then synthesized by the enzyme 5-hydroxyindole-O-methyltransferase and becomes melatonin. After production, melatonin is secreted into the bloodstream.

Along with being an important regulator of many of the body’s other hormones, melatonin has several key effects on the human body. First, it is responsible for controlling the body’s circadian rhythm — the internal clock that plays a role in when we sleep and wake up. Melatonin is stimulated by darkness and inhibited by bright light.

Second, melatonin controls the timing and release of female reproductive hormones; therefore, it controls the frequency and duration of menstrual cycles. Additionally, it determines when a young woman begins having her menstrual cycles, and when a woman stops having them (menopause).

Finally, melatonin also has antioxidant properties. Some studies suggest that it may help to strengthen the immune system.
Pharmacological Uses

Melatonin supplements are available in many forms: tablets, capsules, cream, and lozenges. In research studies, melatonin has been shown to have many uses. However, the effects of taking melatonin supplements over a long period of time have not yet been studied, so any potential side effects are not yet known. Some of the conditions in which melatonin has been proven an effective treatment in research studies are listed below:

Insomnia
Because of its role in controlling the circadian rhythm, melatonin may help to induce sleep in people who suffer from insomnia. Studies have shown that melatonin treatment helps to decrease the amount of time needed to fall asleep, increase the amount of time a person sleeps, and decrease tiredness during the day. Additionally, it may also help to prevent jet lag when people travel across several time zones.

Osteoporosis
Melatonin has been shown to stimulate osteoblasts — the cells that promote bone growth. Research shows that melatonin may be an effective preventative treatment against osteoporosis in both elderly people and menopausal women with diminished melatonin levels.

Seasonal Affective Disorder (SAD)
In some studies, melatonin has been shown to be an effective treatment against SAD — a depressive disorder that generally occurs during dark and or rainy seasons. However, the studies that have been conducted have been small scale, and more research is necessary before melatonin can be considered proven treatment of SAD symptoms.

Menopause
Many women going through menopause suffer from sleep disorders. Melatonin may help to regulate sleep cycles in these cases.

Cancer
Melatonin supplements have been shown to decrease or prevent weight loss in cancer patients. Additionally, both breast prostate cancers are related to depleted melatonin levels. Melatonin supplements may help to prevent these types of cancers. In prostate cancer, melatonin has been shown to inhibit the growth of prostate cancer cells. In breast cancer, melatonin may even enhance chemotherapy treatments by preventing the depletion of blood platelets — a common complication of chemotherapy treatment called thrombocytopenia.

Sarcoidosis
Sarcoidosis is a condition in which fibrous tissue develops in the lungs. Generally, this condition is treated with steroids. However, melatonin may help to treat this condition in cases where steroid treatment is ineffective.

Rheumatoid Arthritis
Lowered melatonin levels are often found in patients with rheumatoid arthritis. For this reason, melatonin supplements may help to treat and prevent symptoms of rheumatoid arthritis.

Attention Deficit Hyperactive Disorder (ADHD)
Though melatonin does not suppress any of the behavioral symptoms of ADHD, it does help to treat the sleeplessness that is often associated with the disease.

Sunburn
Some studies have shown that melatonin helps to prevent the redness and skin damage related to sunburn. For this treatment, melatonin is available in a skin cream, generally paired with vitamin E.