Studies suggest that 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 the scientific literature suggests that melatonin supplements may help prevent jet lag, particularly in people who cross 5 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.
Several human studies have measured the effects of melatonin supplements on sleep in healthy people. A wide range of doses has been used, often taken by mouth 30 to 60 minutes prior to sleep time. Results have been mixed. Some evidence suggests that melatonin may work best for people over 55 who have insomnia. One study of 334 people aged 55 and older found that sustained-release melatonin seemed to help people fall asleep faster, sleep better, be more alert in the morning, and improve quality of life in people with primary insomnia.
Several studies show melatonin has cardioprotective properties, including antioxidant and anti-inflammatory effects. Research also suggests that melatonin may help lower blood pressure levels and improve cholesterol profiles. More research is needed.
Melatonin supplements may improve sleep problems associated with menopause. Other studies suggest it may help restore quality of life and prevent bone loss among perimenopausal women. 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.
Some research suggests 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. More research is needed. You should never combine melatonin with sedative medications unless you are under the strict supervision of a health care provider.
Several studies suggest that low 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 than 28% of the women. Women with breast cancer should ask their doctors before taking melatonin.
Studies show that men 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. Interestingly, since meditation may cause melatonin levels to rise it appears to be a valuable addition to the treatment of prostate cancer. More research is needed before doctors can make recommendations in this area. Men with prostate cancer should talk to their doctor before taking medication.
Attention Deficit Hyperactivity Disorder (ADHD) and Autism
Some evidence suggests that melatonin may help promote sleep in children with ADHD or autism, although it does not seem to improve the behavioral symptoms of ADHD or autism.
A randomized, placebo-controlled study found that people with fibromyalgia experienced a significant reduction in their symptoms when they took a melatonin supplement either alone or in conjunction with fluoxetine (Prozac).
- Sunburn -- Preliminary studies suggest that gels, lotions, or ointments containing melatonin may protect against sunburn and other skin damage. Studies examined using melatonin alone or combined with topical vitamin E prior to UV light exposure from the sun.
- Irritable Bowel Syndrome (IBS) -- Preliminary research suggests that people with IBS who take melatonin reduce some symptoms, such as abdominal pain. Results are mixed as to whether melatonin may help improve other symptoms, such as bloating and frequency of bowel movements.
- Epilepsy -- Some studies suggest melatonin may reduce the frequency and duration of seizures in children with epilepsy, but other studies suggest melatonin may increase the frequency of seizures. Do not take melatonin for epilepsy, or give it to a child, without talking to your doctor first.
- Sarcoidosis -- Some researchers suggest that melatonin may be effective in the treatment of pulmonary sarcoidosis. Talk to your doctor.
- Assisted Reproduction -- Interestingly, preliminary studies suggest melatonin supplementation in the eggs of women with polycystic ovarian syndrome could improve egg maturation and pregnancy rates.
- Other Uses -- Preliminary evidence suggests that melatonin may play a role in pain modulation and digestive function. More research is needed.
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