Chronic exposure to 25-80-mu T, 200-Hz magnetic field does not influence serum melatonin concentrations in patients with low back pain

There is substantial evidence that magnetic field (MF) exposure influences melatonin secretion in animals. However, data on its influence on human mel atonin levels are scarce, and seemingly contradictory. Because of its many beneficial effects, very low-frequency MF exposure is used in physiotherapy of same neurological diseases and overloading syndromes of the locomotor s ystem. In previous studies, we observed a decrease in human serum melatonin nocturnal concentrations after exposure to MF (2.9 mT, 40 Hz), and we sugg ested that differences among various studies may depend on different charac teristics of the applied MF. Therefore, in the present study, we examined w hether 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) suf fering from low back pain. Patients were exposed to a pulsating MF (inducti on: 25-80 mu T; frequency: 200 Hz, modulated, automatically programmed; com plex saw-like impulse shape; bipolar) generated by a Quatronic MRS 2000 app aratus ("magnetic bed") for 3 wk (5 days/wk, twice a clay at 08:00 and 13:0 0 hr for 8 min each), applied to the whole body in patients laying in a hor izontal position. The study was performed in spring. Diurnal serum melatoni n profiles were estimated 1 day before exposure to MF (baseline), and 1 day and 1 month after the last exposure. No changes in melatonin concentration s were observed either after 1 day or after 1 month following the exposure in comparison to baseline.