Chronic exposure to 25-80-microT, 200-Hz magnetic field does not influence serum melatonin concentrations in patients...

There is substantial evidence that magnetic field (MF) exposure influences melatonin secretion in animals. However, data on its influence on human melatonin levels are scarce, and seemingly contradictory. Because of its many beneficial effects, very low-frequency MF exposure is used in physiotherapy of some neurological diseases and overloading syndromes of the locomotor system. In previous studies, we observed a decrease in human serum melatonin nocturnal concentrations after exposure to MF (2.9 mT, 40 Hz), and we suggested that differences among various studies may depend on different characteristics of the applied MF. Therefore, in the present study, we examined whether or not MF of different parameters exerts the same effect. The study was performed in seven men (mean age: 36.7 +/- 3.8 years; range: 32-42) suffering from low back pain. Patients were exposed to a pulsating MF (induction: 25 80 microT; frequency: 200 Hz, modulated, automatically programmed; complex saw-like impulse shape; bipolar) generated by a Quatronic MRS 2000 apparatus ("magnetic bed") for 3 wk (5 days/wk, twice a day at 08:00 and 13:00 hr for 8 min each), applied to the whole body in patients laying in a horizontal position. The study was performed in spring. Diurnal serum melatonin profiles were estimated 1 day before exposure to MF (baseline), and 1 day and 1 month after the last exposure. No changes in melatonin concentrations were observed either after 1 day or after 1 month following the exposure in comparison to baseline.