Nocturnal magnetic field exposure: gender-specific effects on heart rate variability and sleep

Abstract Objective : To determine if controlled exposure to power-frequency magnetic fields alters heart rate variability (HRV) and polysomnographic endpoints in healthy men ( n =22) and women ( n =24), 40–60 years of age. Methods : A randomized, double-blind, crossover design was used. Study endpoints collected during all-night exposure to 60 Hz magnetic fields at an occupational intensity (resultant flux density=28.3 microTesla, μT) were compared to similar endpoints obtained under equivalent, counterbalanced, no-exposure (≤0.2 μT) control conditions. Results : Older men, but not women, exposed to the magnetic fields showed power reductions in the LF band of the HRV frequency spectrum, which is associated with sympathetically-mediated blood pressure and thermoregulatory control ( P P =0.03), and strong trends for reductions in sleep efficiency ( P =0.06) and total sleep time ( P =0.06). Conclusions : The gender-specific effects seen here with older volunteers replicate the results of previous exposure studies with younger men and women.