Monday, 17 June 2019

Mobile phone and base station signals do not affect sleep says latest research

SLEEP-emailScientists have found no link between sleep quality and exposure to mobile and cordless phones or exposures from nearby mobile phone masts after studying a group of residents in Basel in northwest Switzerland for 12 months. This has also been confirmed by a recent Australian study which also raised concerns about the reliability of this type of research.


“We did not find evidence for adverse effects on sleep quality from RF-EMF [radiofrequency electromagnetic field] exposure in our everyday environment,” the Swiss researchers concluded.


Lead researcher Evelyn Mohler of the Swiss Tropical and Public Health Institute and colleagues from the University of Basel studied 955 randomly selected people from the Basel area to see if exposure to mobile and cordless phones or base stations changed their sleep quality.


“In the last two decades, emerging wireless technologies like mobile or cordless phones have led to increasing exposure to radiofrequency electromagnetic fields (RF-EMF) in everyday life,” the researchers said.


“As a consequence, public concern about possible health effects due to RF-EMF exposure arose and various representative population surveys in Europe reported that sleep disturbances were the most common health complaints attributed to RF-EMF exposure”.


The study participants filled out a questionnaire in 2008 and a follow-up questionnaire in 2009 to assess their daytime sleepiness and any sleep disturbances, such as, difficulty in falling asleep, fitful sleep, waking phases during night, and waking too early in the morning.


The researchers also asked about the participant’s average mobile and cordless phone use during the previous 6 months and checked this with their phone account records.


The researchers also estimated the local exposure in home from nearby base stations and any other radio frequency source.


To further confirm the accuracy of the study the researchers looked more closely at 119 participants who were exposed the most.  These people wore devices on their wrists for two weeks which measured their sleep quality and meters were placed next to their beds to measure their radio frequency exposure.


“There was neither a consistent increase in self-reported daytime sleepiness or sleep disturbances if exposure at baseline was high, nor was a change in RF-EMF exposure consistently accompanied by a corresponding change in daytime sleepiness,” the researchers said.


The study was funded by the Swiss National Science Foundation.


Australian study questions the reliability of sleep research

A recent Australian study conducted to examine the effects of mobile phone calls before bedtime reconfirmed the results of an earlier study which showed no effect on the overall quality of sleep, but evidence of individual sensitivity raises question about the reliability this type of research.


In 2005 PhD student Sarah Loughran undertook the research which compared the brain waves of volunteers not exposed to mobiles before sleep with people exposed to mobile phone emissions.


Dr Sarah Loughran2  

Dr Sarah Loughran


For two consecutive nights, volunteers were exposed for 30 minutes to a mobile phone, positioned in a cradle next to their head, before going to sleep.


On one night the phone was continuously transmitting and on the other it was turned off - a so-called 'sham control'. The volunteers didn't know whether the phone was turned on or not.


“The results show that there is an increase in brain wave activity in the first part of sleep. It was an increase in what’s known as alpha brain wave activity and at this stage, we’re not entirely sure what this means,” Dr Loughran said.


Nevertheless, Ms Loughran said getting a good night's sleep did not appear to be affected by the mobile phone radiation.


“We didn’t find any changes in the amount of time it takes to get to sleep or the total time they slept,” Dr Loughran said.


Ms Loughran repeated the experiment on the same participants and found similar results, in the second study published in Bioelectromagnetics earlier this year.


Brainwave monitoring during sleep showed, in keeping with previous findings, that exposure to mobile phones did not affect the overall quality of sleep but it once again increased EEG activity during the first 30 minutes of non-rapid eye movement (non-REM) sleep.


But what was most interesting was the EEG activity increase was more prominent in those individuals who had shown an increase in the previous study.


While the researchers found no impact on the quality of sleep, they say the findings on individual sensitivity now question the reliability of this type of research.


“Importantly, this low-level effect was also shown to be sensitive to individual variability,” the researchers said.


“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, we may need to rethink the interpretation of results and the manner in which research is conducted in this field.”


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