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

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<0.04). Older women, but not men, exposed to the fields showed a pattern of disrupted sleep, with reductions in the duration of REM sleep (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.