As you know, I recommend melatonin as a remedy for jet lag. The dose is 2.5 mg to 3.0 mg placed under the tongue at bedtime for a night or two after arriving in a distant time zone. Over the past several years, there has been a wealth of research on other uses of melatonin - from its benefits as an antioxidant and an alleged anti-aging supplement to its effects on sleep disturbances and seasonal affective disorder (SAD) to the treatment of endocrine problems and even cancer. Much of the research done to date has been in cultured cells, in animals or in very small numbers of patients. It is important to keep in mind that melatonin is a hormone generally required in small doses; the doses used in some of these studies have been much higher than those needed for normal hormonal balance. We don't yet know what side effects these larger doses might cause over long periods of time. In some of the studies with high dose melatonin described below, the only side effects reported were headache and sleepiness among a small number of the patients participating.
Of all the indications for which melatonin is being studied, the one that seems to have the most potential is the use of high-dose melatonin as an adjunctive therapy for cancer.
Preliminary clinical studies suggest that melatonin may work well in the support of advanced cancer patients as well as to limit some of the toxic side effects of chemotherapy. Patients with advanced solid tumors given high dose melatonin (20 mg at night) along with chemotherapy showed a significantly higher percentage of stabilization and one-year survival than those receiving supportive care alone. In addition, melatonin seemed to help the patients by reducing the side effects of chemotherapy including lack of energy, mouth ulcers, peripheral neuropathy, loss of blood platelets and heart muscle damage.
I believe that melatonin may be beneficial for patients with advanced cancer who have not been helped by conventional treatment or have no standard treatment options left. However, more studies are needed to ensure that high doses are safe when taken over the long-term.
Clearly, we're just beginning to learn about melatonin's complex effects. Stay tuned. I'll report new developments as they occur.
Andrew Weil, M.D.