Melatonin For Resistance-Training Athletes

Can melatonin have beneficial effects for athletes other than on circadian rhythms?  This paper says yes.  Abstract:

Previous data showed that the administration of high doses of melatonin improved the circadian system in athletes. Here, we investigated in the same experimental paradigm whether the antioxidant properties of melatonin has also beneficial effects against exercise-induced oxidative stress and muscle damage in athletes. Twenty-four athletes were treated with 100 mg.day-1 of melatonin or placebo 30 min before bedtime during four weeks in a randomized double-blind scheme. Exercise intensity was higher during the study that before starting it. Blood samples were collected before and after treatment, and plasma was used for oxygen radical absorption capacity (ORAC), lipid peroxidation (LPO), nitrite plus nitrate (NOx), and advanced oxidation protein products (AOPP) determinations. Glutathione (GSH), glutathione disulphide (GSSG) levels, and glutathione peroxidase (GPx) and reductase (GRd) activities, were measured in erythrocytes. Melatonin intake increased ORAC, reduced LPO and NOx levels, and prevented the increase of AOPP, compared to placebo group. Melatonin was also more efficient than placebo in reducing GSSG.GSH-1 and GPx.GRd-1 ratios. Melatonin, but not placebo, reduced creatine kinase, lactate dehydrogenase, creatinine, and total cholesterol levels. Overall, the data reflect a beneficial effect of melatonin treatment in resistance-training athletes, preventing extra- and intracellular oxidative stress induced by exercise, and yielding further skeletal muscle protection against exercise-induced oxidative damage.

This, melatonin seems to protect skeletal muscle from oxidative stress damage as it prevents extracellular and intracellular oxidative stress. Interestingly, total cholesterol was reduced as well.

Blindness and Cancer Risk

This is an interesting paper.
 

Melatonin is a hormone primarily produced by the pineal gland at night and is suppressed by exposure to light. Experimental studies have indicated that melatonin may protect against cancer development. In the majority of totally blind people, melatonin is never suppressed by light exposure. The aim of this study was to test the hypothesis that blind people have a decreased cancer incidence, and that this effect is more pronounced in the totally blind than in the severely visually impaired. We identified a cohort of 1,567 totally blind and 13,292 severely visually impaired subjects and obtained information about cancer incidence from the Swedish Cancer Registry. We calculated standardized incidence ratios (SIRs) based on the number of person-years and incidence rates specific for national age, sex, and calendar year. Totally blind people had a lower incidence of all cancers combined [SIR = 0.69; 95% confidence interval (CI) = 0.59-0.82]. The risk reduction was observed in both men and women and was equally pronounced in hormone-dependent tumors as in other types of cancer. In the severely visually impaired, SIR was 0.95 (95% CI = 0.91-1.00). The findings support the hypothesis that blind people have a lower cancer incidence, although other explanations than the higher melatonin exposure must also be considered.

When such epidemiological findings are observed, it is extremely important to follow up and find out why this occurs. And that of course applies not only to this particular finding, but in general to every observation where a specific population has a greater or lesser incidence of some disease. Figuring out why incidence varies could be the first step to designing approaches for prevention and therapy.