Medical/biological study (experimental study)

Pulsed radio-frequency electromagnetic fields: dose-dependent effects on sleep, the sleep EEG and cognitive performance med./bio.

By: Regel SJ, Tinguely G, Schuderer J, Adam M, Kuster N, Landolt HP, Achermann P

Published in: J Sleep Res 2007; 16 (3): 253-258

Aim of study (acc. to author)

To establish a dose-response relationship between the field strength of electromagnetic fields and previously reported effects (see "Related articles") on the brain, the authors aimed to investigate the influence of electromagnetic field exposure by varying the signal intensity (0.2 W/kg; 5 W/kg; sham exposure).

Background/further details

The heads of 15 healthy male subjects was unilaterally exposed for 30 min prior to sleep. During exposure subjects performed cognitive tasks. Immediately after exposure, night-time sleep was polysomnographically recorded for 8 h.

Endpoint

sleep: different sleep variables

Exposure

- mobile communications
- mobile phone
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 900 MHz Modulation type: pulsed Exposure duration: continuous for 30 min	SAR: 0.2 W/kg average over mass (10 g) SAR: 5 W/kg average over mass (10 g)

General information

The study consisted of three sessions separated by 1-week intervals in a randomized double-blind crossover design. Each session consisted of an adaptation night and a subsequent experimental night.

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Exposure duration	continuous for 30 min

Modulation

Modulation type	pulsed
Pulse width	0.577 ms
Duty cycle	21 %
Additional info	GSM-like handset signal (DTX and non-DTX without temporal switching) [Huber et al., 2005] with modulation components of 2, 8, 217 and 1736 Hz and higher harmonics

Exposure setup

Exposure source	planar antennas
Setup	Subjects were exposed unilaterally (left hemisphere) with their heads positioned between two plates to ensure a well-defined position with respect to the planar antennas [Huber et al., 2000, 2003].
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.2 W/kg	average over mass	-	10 g	-
SAR	5 W/kg	average over mass	-	10 g	-

Additional parameter details

The values indicated are peak spatial SARs. The corresponding SAR levels induced in the brain are summarized in a table, providing the 1-g averaged peak spatial SAR, the averaged SAR and SD of the exposed hemisphere, estimations of the inter-subject variations, and assessment of uncertainty.

Measurement and calculation details

For details on signal and dosimetry see [Huber et al., 2003, 2005].

Reference articles

Huber R et al. (2005): Exposure to pulse-modulated radio frequency electromagnetic fields affects regional cerebral blood flow
Huber R et al. (2003): Radio frequency electromagnetic field exposure in humans: Estimation of SAR distribution in the brain, effects on sleep and heart rate
Huber R et al. (2000): Exposure to pulsed high-frequency electromagnetic field during waking affects human sleep EEG

Exposed system:

human
partial body: head (unilateral; left hemisphere)

Methods Endpoint/measurement parameters/methodology

effects on the cardiovascular system: ECG
cognitive/behavioral endpoints: cognitive performance (cognitive tasks (n-back task (1-, 2-, 3-back task); reaction time task, 2-choice reaction time task))
sleep: different sleep variables (e.g. total sleep time, sleep latency, REM sleep latency (polysomnography)); sleep EEG
EMG; EOG

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

Sleep architecture was not affected by electromagnetic field exposure. The sleep EEG revealed a dose-dependent increase of power in the spindle frequency range in non-REM sleep.
Reaction speed decreased with increasing field strength in the 1-back task, while accuracy in the 2-choice reaction time task and N-back task were not affected in a dose-dependent manner.
In conclusion, the data revealed first indications of a dose-response relationship between electromagnetic field intensity and its effects on brain physiology.

Study character:

medical/biological study
experimental study
full/main study
double-blind study, crossover study

Study funded by

Federal Office of Public Health (FOPH; Bundesamt für Gesundheit), Switzerland
Forschungsstiftung Mobilkommunikation (FSM; Research Foundation on Mobile Communication; at the Swiss Federal Institute of Technology Zurich (ETH)), Switzerland
Swiss National Science Foundation (SNF)

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