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, microT) were compared to similar endpoints obtained under equivalent, counterbalanced, no-exposure (< or =0.2 microT) 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.
Graham
C
C
Midwest Research Institute, 425 Volker Boulevard, Kansas City, MO 64110, USA. cgraham@mriresearch.org
Sastre
A
A
Cook
M R
MR
Gerkovich
M M
MM
D000328:Adult; D000367:Age Factors; D001794:Blood Pressure / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*