The aim of the study was to investigate whether the electro-magnetic field (EMF) emitted by digital radiotelephone handsets affects brain physiology. Healthy, young male subjects were exposed for 30 min to EMF (900 MHz; spatial peak specific absorption rate 1 W/kg) during the waking period preceding sleep. Compared with the control condition with sham exposure, spectral power of the EEG in non-rapid eye movement sleep was increased. The maximum rise occurred in the 9.75–11.25 Hz and 12.5–13.25 Hz band during the initial part of sleep. These changes correspond to those obtained in a previous study where EMF was intermittently applied during sleep. Unilateral exposure induced no hemispheric asymmetry of EEG power. The present results demonstrate that exposure during waking modifies the EEG during subsequent sleep. Thus the changes of brain function induced by pulsed high-frequency EMF outlast the exposure period.
1Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich
2Laboratory for Integrated Systems, ETH Zürich, CH-8092 Zürich
3Foundation for Research on Information Technologies in Society (IT'IS), CH-8045 Zürich, Switzerland
4Corresponding Author: Peter Achermann
Acknowledgements: This study was supported by Swiss National Science Foundation, grant 3100-053005.97, the Human Frontiers Science Program grant RG-81/96 and the Swiss Federal Office of Public Health. We thank Professor Irene Tobler for comments on the manuscript.
Received 18 July 2000; accepted 3 August 2000