06/06/2012
Sleep EEG Alterations: Effects of Pulsed Magnetic Fields Versus Pulse-Modulated Radio Frequency Electromagnetic Fields
Marc R. Schmid, Manuel Murbach, Caroline Lustenberger, Micheline Maire, Niels Kuster, Peter Achermann, and Sarah P. Loughran, Journal of Sleep Research, 10pp., online ahead of print June 22, 2012
Studies have repeatedly shown that EEG power during sleep is enhanced in the spindle frequency range following pulse-modulated RF electromagnetic field exposures. Signals used in previous studies also had significant harmonic components above 20 Hz. The current study aimed to: (i) determine if modulation components above 20 Hz are necessary to alter the EEG; and (ii) test the demodulation hypothesis, i.e. if the same effects occur after magnetic field exposure with the same pulse sequence.
In a randomized double-blind crossover design, 25 young healthy men were exposed at weekly intervals to three different conditions for 30 minutes before sleep. The conditions were a 2-Hz pulse-modulated radio frequency field, a 2-Hz pulsed magnetic field, and sham.
Radio frequency exposure increased EEG power in the spindle frequency range. Furthermore, delta and theta activity (non-rapid eye movement sleep), and alpha and delta activity (rapid eye movement sleep) were affected following both exposure conditions (RF and magnetic field). No effect on sleep architecture and no clear impact of exposure on cognition was observed.
The scientific and technical impact of the study can be summarized as:
- Both pulse-modulated RF exposure and pulsed magnetic fields affect brain physiology.
- The presence of frequency components above 20 Hz is not fundamental for these effects to occur.
- Because responses were not identical for all exposures, the study does not support the hypothesis that effects of radio frequency exposure are based only on demodulation of the signal.