Study type: Medical/biological study (experimental study)

Sleep after mobile phone exposure in subjects with mobile phone-related symptoms. med./bio.

Published in: Bioelectromagnetics 2011; 32 (1): 4-14

Aim of study (acc. to author)

To study the effects of radiofrequency exposure (GSM) on self-evaluated sleepiness and objective EEG measures during sleep in a non-sensitive and a sensitive group (with symptoms in relation to mobile phone use).

Background/further details

48 subjects (mean age 28 years; 27 females, 21 males) were exposed for 3 h (19:30-22:30; active or sham exposure) prior to sleep. The test sessions were separated by at least one week. The mobile phone sensitive group consisted of 23 subjects with GSM mobile phone-related symptoms (15 females) and the non-sensitive group, without such symptoms, consisted of 25 subjects (12 females).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 884 MHz
Modulation type: AM, pulsed
Exposure duration: continuous for 3 hr

Exposure 1

Main characteristics
Frequency 884 MHz
Type
Exposure duration continuous for 3 hr
Modulation
Modulation type AM, pulsed
Pulse width 0.577 ms
Additional info

amplitude modulation frequencies: 2, 8, 217 and 1736 Hz 11 s non-GSM-DTX mode, 5 s GSM-DTX mode

Exposure setup
Exposure source
Setup low-weight, stacked, micropatch antenna fixed on a headset, balanced by a counterweight, antenna placed on the left side of the head and a small ceramic plate which was heated to 39° C +/- 0.2° C was fixed to the left ear lobe (to mimic the sensation from a warm phone); test persons placed in a room with RF absorbers on three sides
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.4 W/kg average over time - 10 g -
SAR 1.95 W/kg peak value - 10 g during non-GSM-DTX mode
SAR 1.8 W/kg peak value - 1 g gray matter
SAR 0.2 W/kg spatial average - 1 g gray matter
SAR 0.18 W/kg spatial average - 1 g thalamus

Reference articles

  • Hillert L et al. (2008): The effects of 884 MHz GSM wireless communication signals on headache and other symptoms: an experimental provocation study.
  • Kuster N et al. (2006): Methodology of detailed dosimetry and treatment of uncertainty and variations for in vivo studies.
  • Kuster N et al. (2004): Guidance for exposure design of human studies addressing health risk evaluations of mobile phones.
  • Huber R et al. (2002): Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG.

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 data showed that following exposure, time in sleep stages 3 and 4 (so-called "slow-wave sleep", deep sleep phase) decreased by 9.5 minutes (12% out of a total of 78.6 minutes), and time in sleep stage 2 increased by 8.3 minutes (4% out of a total of 196.3 minutes) compared to sham exposure. The latency to sleep stage 3 was also prolonged by 4.8 min after exposure.
Power density spectral analysis of the EEG indicated an enhanced activation in the frequency ranges 0.5-1.5 and 5.75-10.5 Hz (representing parts of delta wave, theta wave and alpha wave frequency bands) during the first 30 min of sleep stage 2. During the full first hour of sleep stage 2 the spectral density increased particularly within the frequency range of 7.5-11.75 Hz. During the second hour of the sleep stage 2 activity was elevated within the frequency range 4.75-8.25 Hz. No pronounced power changes were observed in slow-wave sleep (sleep stages 3+4) or for the third hour of sleep stage 2.
No differences were found between non-sensitive controls and sensitive subjects with prior complaints of mobile phone-related symptoms.
The data confirm previous findings (see "realted articles") that radiofrequency exposure increased the spectral density of the alpha wave range in the sleep EEG, and indicated moderate impairment of slow-wave sleep. Furthermore, reported differences in sensitivity to mobile phone use were not reflected in sleep parameters.

Study character:

Study funded by

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