Study type: Medical/biological study (experimental study)

Inter-individual and intra-individual variation of the effects of pulsed RF EMF exposure on the human sleep EEG med./bio.

Published in: Bioelectromagnetics 2015; 36 (3): 169-177

Aim of study (acc. to author)

The effects of exposure of young meninges to a 900 MHz electromagnetic field prior to sleep on the brain activity during sleep should be investigated.

Background/further details

The study aimed to investigate inter-individual variation and intra-individual stability of the effects of pulsed radiofrequency exposure on human sleep EEG, as former studies revealed striking inter-individual differences and intra-individual stability (i.e. reproducibility of effects in the same subject) has not been well studied so far.
A total of 20 healthy male subjects participated in 4 night-sessions with a 1-week interval (one night per week on the same weekday). In 2 of those nights, subjects were exposed to the electromagnetic field prior to their scheduled bedtime, in the 2 other nights, subjects were sham-exposed. In a randomized, double-blind, cross-over study design, subjects had one of the 2 exposure orders: sham-exposure/exposure/sham-exposure/exposure or exposure/sham-exposure/exposure/sham-exposure. After real or sham exposure, an EEG cap was applied to the subjects resulting in a 30 min time window between end of exposure and start of sleep recording (lights out).
One subject was excluded from analysis due to poor sleep and EEG signal quality , so a total of 19 subjects were evaluated.



Exposure Parameters
Exposure 1: 900 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 minutes (in each of 2 sessions)

Exposure 1

Main characteristics
Frequency 900 MHz
Exposure duration continuous for 30 minutes (in each of 2 sessions)
Modulation type pulsed
Repetition frequency 2 Hz
Additional info

peak-to-average ratio of 4; higher harmonics were reduced by applying a 20 Hz Gaussian low-pass filter to a rectangular pulse sequence

Exposure setup
Exposure source
Distance between exposed object and exposure source 110 mm
Setup a lateral patch antenna in a plastic box-casing was used to expose left head hemisphere; an identical box-casing was installed on the right side to prevent knowledge about the exposure; exposure system was fully computer controlled
Sham exposure A sham exposure was conducted.
Measurand Value Type Method Mass Remarks
SAR 2 W/kg spatial average estimated 10 g peak value for whole head
SAR 2.12 W/kg spatial average estimated 1 g peak value for lateral cortex, ± 12% standard deviation
SAR 0.62 W/kg - estimated - for thalamus, ± 35% standard deviation
power 4 W - - - forward power to the antenna, ± 6% standard deviation

Reference articles

  • Murbach M et al. (2014): Modeling of EEG electrode artifacts and thermal ripples in human radiofrequency exposure studies
  • Schmid MR et al. (2012): Sleep EEG alterations: effects of pulsed magnetic fields versus pulse-modulated radio frequency electromagnetic fields
  • Murbach M et al. (2012): Exposure system to study hypotheses of ELF and RF electromagnetic field interactions of mobile phones with the central nervous system
  • Christ A et al. (2010): Age-dependent tissue-specific exposure of cell phone users

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The delta wave-theta wave activity during non-REM sleep was significantly increased in several fronto-central brain regions after exposure compared to sham exposure sessions. However, this effect was not reproducible in the same subjects. All other parameters did not show significant differences between exposure and sham exposure conditions at all and no inter-individual or intra-individual correlations.
The authors conclude that no reproducible effects of exposure of young males to a 900 MHz electromagnetic field prior to sleep on the brain activity during sleep were observed.

Study character:

Study funded by

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