Evidence continues to accumulate regarding the antioxidant benefits of
melatonin. In laboratory studies, melatonin has been found to stimulate
natural antioxidant systems such as superoxide dismutase and glutathione
peroxidase, in addition to offering protection to the DNA present within
cells. While these effects have been observed primarily using pharmacological
(very large) doses of melatonin, in a small number of experiments melatonin
has been found to have antioxidant properties in small, physiological doses as
well. The ability of melatonin in inhibiting oxidative damage has been tested
in a variety of neurological diseases where free radicals have been suspected
as being in part causative of the condition. Thus, melatonin has been shown to
reduce amyloid protein toxicity of Alzheimer's disease, to reduce oxidative
damage in some types of Parkinson's disease, to reduce brain injury when
exposed to low blood or oxygen flow, and to lower brain damage due to a
variety of neural toxins. Since melatonin levels fal1 markedly in advanced
age, the implication of these findings is that the loss of this antioxidant
may contribute to the incidence or severity of some age-associated
neurodegenerative diseases.
Comments: Until more is known about melatonin's long-term effects, my
recommendations are to use small doses of this hormone for sleep in the range
of 0.3 to 1 mg and not to exceed the use of this hormone more frequently than
two or three nights a week. Many people become tolerant to the sleep inducing
effects of melatonin when they use it too frequently. Unfortunately, we don't
know at this time whether small amounts of melatonin used for sleep purposes
provides any significant antioxidant protection. It's possible that larger
amounts of melatonin offer more antioxidant protection but then we run the
risk of unknown long-term side effects from high dosage use for prolonged
periods.
Reiter RJ. Oxidative damage in the central nervous system: protection by
melatonin. Prog Neurobiol 1998 Oct;56(3):359-84