Study type: Medical/biological study (experimental study)

Individual differences in the effects of mobile phone exposure on human sleep: Rethinking the problem. med./bio.

Published in: Bioelectromagnetics 2012; 33 (1): 86-93

Aim of study (acc. to author)

To replicate previous results of an enhancement of EEG power in the 11.5-12.25 Hz frequency range and to determine whether mobile phone emissions have different effects on both the sleep EEG and sleep quality of different individuals by re-testing a subset of participants from a previous study (Loughran et al. 2005).

Background/further details

20 healthy volunteers (7 males, 13 females) who were participants in the previous study were retested and underwent an adaptation night followed by two experimental nights in which they were randomly exposed to two conditions (active and sham exposure), followed by a full-night sleep episode. Participants were divided into two groups based on the data of the previous experiment: "increaser" group and "decreaser" group according to an increase/decrease in spectral power in the 11.5-12.25 Hz frequency range during non-REM sleep.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 894.6 MHz
Modulation type: pulsed
Exposure duration: continuous for 30 min
  • SAR: 0.11 W/kg average over mass (10 g)
  • SAR: 0.674 W/kg peak value (10 g)
  • power: 2 W peak value
  • power: 0.25 W mean

Exposure 1

Main characteristics
Frequency 894.6 MHz
Type
Exposure duration continuous for 30 min
Modulation
Modulation type pulsed
Pulse width 576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Exposure setup
Exposure source
  • Nokia 6110 GSM handset
Setup mobile phone attached to an adjustable head cradle which was worn by the test person during exposure; phone positioned over the right temporal region and adjusted towards the corner of the mouth, comparable to normal use; ear plug placed in the test person's right ear; audio circuits of the phone disconnected, a padding placed between the handset and its cover, and phone set to send with maximum power
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.11 W/kg average over mass measured 10 g -
SAR 0.674 W/kg peak value calculated 10 g -
power 2 W peak value - - -
power 0.25 W mean - - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

No significant change in power was observed between the active and sham exposure conditions in the 12.25-13.5 Hz and 13.5-14 Hz frequency ranges, either overall, or between the "increaser" group and the "decreaser" group. No significant change was found between the active exposure and sham exposure for either sleep latency, REM sleep latency, sleep duration, sleep efficiency, number of arousals and Karolinska Sleepiness Scale score.
However, the EEG spectral power was increased in the 11.5-12.25 Hz frequency range in the first 30 min of non-REM sleep following active exposure. This increase was more prominent in the participants that showed an increase in the original study ("increaser" group). These data confirm the previous findings of mobile phone-like emissions affecting the EEG during non-REM sleep (see above). Importantly, this low-level effect was also shown to be sensitive to individual variability. Furthermore, this indicates that previous negative results are not strong evidence for a lack of an effect and, given the far-reaching implications of mobile phone research, the authors conclude that it may need to rethink the interpretation of results and the manner in which research is conducted in this field.

Study character:

Study funded by

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