The use of mobile phones is continually increasing throughout the world, with
recent figures showing that there are currently more than 2 billion mobile
phone users worldwide. However, despite the recognised benefits of the
introduction and widespread use of mobile phone technologies, concerns
regarding the potential health effects of exposure to the radiofrequency
electromagnetic fields emitted by mobile phone handsets have similarly
increased, leading to an increase in demand for scientific research to
investigate the possibility of health effects related to the use of mobile
phones.
An increasing amount of radiofrequency bioeffects research related to mobile
phone use has focussed on the possible effects of mobile phone exposure on
human brain activity and function, particularly as the absorption of energy in
the head and brain region is much higher than in other body regions, which is
a direct result from the close proximity of the mobile phone to the head when
in normal use. In particular, the use of sleep research has become a more
widely used technique for assessing the possible effects of mobile phones on
human health and wellbeing, and is particularly useful for providing important
information in the establishment of possible radiofrequency bioeffects,
especially in the investigation of potential changes in sleep architecture
resulting from mobile phone use.
A review of the previous literature showed that a number of studies have
reported an increase in the electroencephalogram spectral power within the 8
� 14 Hz frequency range in both awake and sleep states following
radiofrequency electromagnetic field exposure. In regards to sleep, the
enhancements reported have not been entirely consistent, with some early
studies failing to find an effect, while more recent studies have reported that
the effect differs in terms of particular frequency range. However, in general
the previous literature suggests that there is an effect of mobile phone
emissions on the sleep electroencephalogram, particularly in the frequency
range of sleep spindle activity.
In addition to changes in spectral power, changes in other conventional sleep
parameters and the production and secretion of melatonin have also been
investigated, however, there has been little or no consistency in the findings
of previous studies, with the majority of recent studies concluding that there
is no influence of mobile phone radiofrequency fields on these parameters of
sleep or melatonin.
Following a detailed review of the previous research, the current study was
developed with the aim to improve on previous methodological and statistical
limitations, whilst also being the largest study to investigate mobile phone
radiofrequency bioeffects on human sleep. The principle aims were thus to
test for the immediate effects of mobile phone radiofrequency
electromagnetic fields on human sleep architecture and the secretion of the
pineal hormone, melatonin.
The experiment included 50 participants who were randomly exposed to
active and sham mobile phone exposure conditions (one week apart) for 30
minutes prior to a full night-time sleep episode. The experimental nights
employed a randomised exposure schedule using a double-blind crossover
design. Standard polysomnography was used to measure subsequent sleep,
and in addition, participants were required to provide urine samples
immediately following exposure and upon waking in the morning. A full
dosimetric assessment of the exposure system was also performed in order
to provide sufficient details of the exposure set-up used in the current thesis
and to account for the lack of detailed dosimetric data provided in the
majority of previous studies.
The results of the current study suggest that acute exposure to a mobile
phone prior to sleep significantly enhances electroencephalogram spectral
power in the sleep spindle frequency range compared to the sham exposure
condition. The current results also suggest that this mobile phone-induced
enhancement in spectral power is largely transitory and does not linger
throughout the night. Furthermore, a reduction in rapid eye movement sleep
latency following mobile phone exposure was also found compared to the
sham exposure, although interestingly, neither this change in rapid eye
movement sleep latency or the enhancement in spectral power following
mobile phone exposure, led to changes in the overall quality of sleep.
Finally, the results regarding melatonin suggested that, overall, overnight
melatonin secretion is unaffected by acute exposure to a mobile phone prior
to sleep.
In conclusion, the current study has confirmed that a short exposure to the
radiofrequency electromagnetic fields emitted by a mobile phone handset
immediately prior to sleep is sufficient to induce changes in brain activity in
the initial part of sleep. The consequences or functional significance of this
effect are currently unknown and it would be premature to draw conclusions
about possible health consequences based on the findings of the current
study.
| Identifer | oai:union.ndltd.org:ADTP/216650 |
| Date | January 2007 |
| Creators | Loughran, Sarah Patricia, n/a |
| Publisher | Swinburne University of Technology. |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.swin.edu.au/), Copyright Sarah Patricia Loughran |
Page generated in 0.0023 seconds