Melatonin is a hormone secreted by the pineal gland in the brain. It helps regulate other hormones and maintains the body's circadian rhythm. The circadian rhythm is an internal 24-hour “clock” that plays a critical role in when we fall asleep and when we wake up. When it is dark, your body produces more melatonin; when it is light, the production of melatonin drops. Being exposed to bright lights in the evening or too little light during the day can disrupt the body’s normal melatonin cycles. For example, jet lag, shift work, and poor vision can disrupt melatonin cycles.
It also helps determine when a woman starts to menstruate, the frequency and duration of menstrual cycles, and when a woman stops menstruating (menopause).And has strong antioxidant effects.
Some researchers also believe that melatonin levels drop as we age(as in the diagram).Some people think lower levels of melatonin may explain why some older adults have sleep problems and tend to go to bed and wake up earlier than when they were younger.
Uses:
1-Insomnia
Melatonin supplements may help people with disrupted circadian rhythms (such as people with jet lag or those who work the night shift) and those with low melatonin levels (such as some seniors and people with schizophrenia) to sleep better. A review of clinical studies suggests that melatonin supplements may help prevent jet lag, particularly in people who cross five or more time zones.
A few clinical studies suggest that when taken for short periods of time (days to weeks) melatonin is more effective than a placebo in reducing the time it takes to fall asleep, increasing the number of sleeping hours, and boosting daytime alertness. It’s not clear how well melatonin works, however – some studies suggest that it only reduces the amount of time to fall asleep by a few minutes.
2-Menopause
Melatonin supplements may help with sleep problems associated with menopause. However, it does not appear to relieve other symptoms of menopause, such as hot flashes. Peri- or postmenopausal women who use melatonin supplements should do so only for a short period of time since long term effects are not known.
3-Benzodiazepine Withdrawal
Some clinical research has found that melatonin may help elderly people with insomnia who are tapering off or stopping benzodiazepines such as diazepam (Valium), alprazolam (Xanax), or lorazepam (Ativan). Taking controlled-release melatonin improved sleep quality in those stopping benzodiazepine use.
4-Breast Cancer
Several studies suggest that melatonin levels may be associated with breast cancer risk. For example, women with breast cancer tend to have lower levels of melatonin than those without the disease. Laboratory experiments have found that low levels of melatonin stimulate the growth of certain types of breast cancer cells, while adding melatonin to these cells slows their growth. Preliminary evidence also suggests that melatonin may strengthen the effects of some chemotherapy drugs used to treat breast cancer. In a study that included a small number of women with breast cancer, melatonin (given 7 days before beginning chemotherapy) prevented the lowering of platelets in the blood. This is a common complication of chemotherapy that can lead to bleeding.
In another small study of women who were taking tamoxifen for breast cancer but seeing no improvement, adding melatonin caused tumors to modestly shrink in more 28% of the women. Women with breast cancer should ask their doctors before taking melatonin.
5-Prostate Cancer
Studies show that people with prostate cancer have lower melatonin levels than men without the disease. In test tube studies, melatonin blocks the growth of prostate cancer cells. In one small-scale study, melatonin -- combined with conventional medical treatment -- improved survival rates in 9 out of 14 men with metastatic prostate cancer. More research is needed before doctors can make recommendations in this area.
6-Attention Deficit Hyperactivity Disorder (ADHD)
Some evidence suggests that melatonin may help promote sleep in children in ADHD, although it does not seem to improve the behavioral symptoms of ADHD.
