| Investigation of sleep quality of electrohypersensitive persons living near base stations under residential conditions. |
|
|
Topic Investigation of sleep quality of electrohypersensitive persons living near base stations under residential conditions. Start 01.07.2005 End 31.12.2006 Project Management Technical University Graz Objective An increasing number of persons complains about unspecific health effects, e.g. sleep disorders, and attributes these to the influence of electromagnetic fields of mobile phone base stations. Previous studies on electrohypersensitive persons were predominantly realised as provocation experiments with simulated exposures. If the verification of their electrosensitivity failed, the persons complained, that in the unfamiliar environment and as a result of the EMF-stress, as well as due to too short recovery times, they were in an exceptional situation and therefore did not react as usual. In the experimental approach suggested here the provocation experiments in an unusual environment will be omitted and the reaction to the cancellation of the electromagnetic exposure will be investigated by means of "protection experiments" performed in the flats of the concerned persons. The subjective conviction that high frequency transmitter stations could cause sleep disorders at exposure intensities far below the limits will be investigated. The quality of sleep reported by the participants of the study will be characterised by measurements of long time parameters under residential conditions. Results An appraising review on possible influences of high frequency electromagnetic fields of mobile communication systems on brain function, sleep and human well being and possible causal relations especially with respect to electrohypersensitivity was presented. The methodical approaches of the single papers were critically reviewed. The literature study is available as PDF-file in German (393 KB). Subjectively electrohypersensitive persons, who suffered from substantial sleep disturbances and who were convinced that there is a causal relationship with radiofrequency exposures, were investigated. In the dwellings of the volunteers, the sleep place was shielded by a mobile “canopy” consisting of RF-absorbing material (verum conditions). The shielding factor amounted to about 20 dB. In addition an apparently identical but not shielding material was used (sham conditions). Under control conditions no canopy was present. Under each of the respective conditions three nights were investigated in a randomized double-blind design. The following parameters were sampled each night:
In the field study the sleep quality of 20 volunteers was investigated during 214 nights using polysomnography and standardized questionnaires. The results were pooled with data from 261 nights of 24 volunteers, gained in a preceding study (EPROS Austria). The statistical evaluation of the results was performed by means of multiple variance analysis. Although it was no selection criterion, it turned out that most of the volunteers exhibited an increased electrosensitivity in comparison to the general population. A variety of cofactors, concerning both personal data and daily events as well as physical boundary conditions, was gained and statistically analyzed, but none of them had an influence on the sleep quality. The measurements of the electromagnetic exposures did not confirm expectations of the volunteers to find atypically high electromagnetic exposure values in their bedrooms. In most dwellings the exposures from radio and TV-transmitters were higher than those from mobile phone base stations. The pooled analyses of all volunteers under control conditions resulted in a statistically not significant trend for a better subjective sleep quality at increasing RF-exposure strength in their dwellings. For a predominant number of volunteers the subjective conviction that RF electromagnetic pollution was the cause of their sleep disturbance could be falsified. For a predominant subset of 26 volunteers (59%) no statistically significant differences of the sleep parameters under the individual conditions could be proven. For eight volunteers (18%) it could be demonstrated that already their belief in RF-shielding improved the subjective perception of sleep quality (placebo-effect). The most objective sleep parameters remained unchanged. It could be proven that three volunteers (7%) had checked the real shielding situation. Therefore, their results had to be rejected as an evidence of a potential causal role of RF exposures. For four volunteers (9 %), a statistically significant influence on the falling asleep behaviour in the sense of prolonged sleep onset latencies could be determined as a result of the decrease of the RF exposures. This is in agreement with some not consistently reproduced results from the scientific literature, according to which an increase in RF exposure results in decreased sleep onset latencies. For three volunteers (7 %), significant changes of individual parameters were found, which did not permit any consistent conclusions. The investigations did not indicate any adverse health effects from RF-EMF exposures on the sleep, in particular also not from those of mobile communications. Likewise no improvement of the sleep quality due to shielding could be proven, however, the shielding also did not impair the sleep quality. The final report can be downloaded as PDF-file (2.218 KB) in German with English summary. References
Conclusions The results of the study are in accordance with current scientific publications, which consistently do not find any causal relationship between subjectively believed electrohypersensitivity and the presence of electromagnetic fields. This is confirmed by the fact that the believe in a shielding significantly improved the subjectively percepted, but not the objectively measured sleep parameters. |