Mobile phone related articles are
Please note that a publication can be assigned to several endpoints, i.e. the sum of publications from the individual thematic points and subpoints can be greater than the total sum of actual publications.
Human sleep is a periodically occurring resting state in which individuals calm down and stop interacting with their environment. The conscious mind and spontaneous movements are attenuated or completely frozen. Sleep consists of different sleep phases that occur in several cycles at night. The amount of cycles and the duration of the single phases vary greatly within and between individuals.
The different stages of sleep, ranging from light sleep to deep sleep, can be classified with 30 sec epochs of polysomnographic recordings of EEG, EOG and EMG. During deep sleep most body functions are attenuated, in contrast to REM sleep that is accompanied by a strong physiological activation. Spontaneous awakening occurs significantly more often after a REM sleep phase. Due to its vegetative and central nervous system activation, REM sleep provides ideal conditions for the transition from sleeping to wake state. Moreover, the REM sleep stage is considered to play a significant role for storage processes in memory.
In the past decades, the incidence of sleep disorders has significantly increased. More than 20% of the population report occasional sleep disturbances, e.g. disturbances in the onset of sleep, sleep quality, sleep patterns or sleep profile. Some persons that are concerned attribute these disturbances to the influences of radio frequency electromagnetic fields emitted from transmitters or mobile phones.
In experimental studies, sleep behaviour is investigated under provocation or protection conditions. Under provocation, the exposure to electromagnetic fields is simulated, while under protection the existing electromagnetic fields get shielded. To investigate the effects of electromagnetic fields on sleep, most experiments are performed with human participants, and the following test procedures are frequently used:
A few epidemiological studies reported references that sleep disturbances might be associated to transmitters (broadcasting station), base stations or mobile phones.
Overall, the existing experimental studies vary strongly in exposure conditions, investigated groups, analyzing methods of the bio-signals and applied statistics. Moreover, laboratory studies have some methodological limitations that have to be considered for the interpretation of results:
Many epidemiological studies have several methodological shortcomings in their exposure estimations and should therefore not be used for causal interpretations. Some of the criteria that affect the validity of the results are:
From 19 available studies (see table: april 2009), six studies investigated sleep quality, five studies investigated sleep profile, two studies investigated sleep disorders and the remaining studies investigated other parameters of sleep, e.g. night sleep, sleep onset or EEG during sleep. All studies were performed with humans and the exposure durations varied between 30 min and repeated exposure over 12 nights. 17 studies were provocation studies i.e. the exposure to electromagnetic fields was studied. In two studies (Leitgeb N, 2007, Leitgeb N et al., 2004), electromagnetic fields were shielded. 15 studies used recorded polysomnographic data of EEG, EOG and EMG, three studies only studied sleep EEG and six studies assessed self-reported sleep data (e.g. Pittsburgh Sleep Quality Index). In sum, ten studies did not provide evidence for detrimental effects of radio frequency electromagnetic fields on sleep, especially not through mobile phones. Seven studies reported effects on REM sleep and sleep EEG, indicating a reduced duration of REM sleep (e.g. Loughran SP et al., 2005, Lebedeva NN et al., 2001). Three studies indicated effects of radio frequency electromagnetic fields on sleep onset behaviour, showing extended sleep onset times both under exposure conditions (Arnetz BB et al., 2007, Hung CS et al., 2007) as well as protective conditions (Leitgeb N, 2007).
Generally, a final evaluation of detrimental effects of radio frequency electromagnetic fields on sleep is a complex and time-consuming process that has to be enforced by an expert body. In the course of such an evaluation, all publications of a certain frequency range types have to be collected and evaluated regarding their quality (e.g. dosimetry, study design, sample size, statistics). The results have to reproducible and should be evaluated with regard to comparable research studies.
At the international level, the WHO is particularly responsible for statements on the effects of electromagnetic fields. For public health related issues, specific recommendations are made available (WHO 2000). At the national German level, the federal office for radiation protection (Bundesamt für Strahlenschutz, BfS) is the responsible authority. They also provide statements on the effects of electromagnetic fields.
In 2009, the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) has published a review on the literature concerning "Brain, cognition and sleep" (BfS 2009). In Germany, the Strahlenschutzkomission (comittee for radiation protection, www.ssk.de) at the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit) also provides statements on the effects of electromagnetic fields. In a Statement from 2008 on the German Mobile Phone Research Programme (Deutsches Mobilfunk-Forschungsprogramm), the committee evaluated the recent state of knowledge of health effects of radio frequency electromagnetic fields on several endpoints. For the topics EEG and sleep quality the committee has concluded, that "previous reports on effects of mobile phone fields on sleep quality cannot be confirmed by the recently conducted studies. A final evaluation can only be made when all the studies have been finished and data have been completely analyzed."
An evaluation of more than 150 scientific studies on radiofrequency exposure of the Swiss Federal Office of the Environment (FOEN) from 2007 summarized the health effects of radio frequency exposure on several endpoints. For the subtopic "sleep (phases and quality)" the following conclusions were drawn: "It is considered likely that exposure to mobile phones changes electric currents in the brain, e.g. spontaneous EEG during sleep. [...] It is also considered likely that changes in sleep phases occur. [...] The observed effects occurred at such low radiation intensities that the conventional thermal causation model alone is not sufficient to explain the effects." Further, FOEN states: "It is not considered likely that sleep stages change under exposure to radio frequency electromagnetic fields [...], e.g. latency until the first REM sleep phase starts. Subjective evaluations have already not been correlated to radio frequency exposure in older studies. Thus exposure effects are not generally experienced negatively."
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