Lifestyle and exercise

Mobile effect on sleep

“Radiation from mobile phones delays and reduces sleep, and causes headaches and confusion, according to a new study”, reported The Independent on Sunday on January 20 2008.

The Daily Telegraph also covered the story, reporting that a study funded by handset manufacturers found that using a mobile before going to bed could damage your health.

The main health risk listed by the newspapers is less time in the deeper stages of sleep that can help the body recuperate. It is suggested that regular late night mobile use by teenagers may even lead to mood and personality changes and problems like ADHD.

This experiment has several important limitations and does not provide sufficient evidence to suggest that mobile use at night is a risk to health. The study only had 71 participants and 38 of them reported suffering from problems that they attributed to mobile use before they entered the study. The small group size and high proportion of people who reported sensitivity to mobile use are unlikely to be representative of the population.

Despite what is reported in the newspapers, there is no suggestion within the research paper they cite that radio waves cause confusion or have any harmful affects upon mood, concentration or personality.

There have been several studies on whether mobiles and radio frequency signals are detrimental to health. The Mobile Telecommunications and Health Research programme 2007 report can be considered as the largest body of work carried out anywhere on electrical hypersensitivity. It reports that a large and rigorous study supported by the programme found “no support for the notion that the aversive symptoms attributed to mobile phone signals by hypersensitive individuals are caused by exposure to such signals.”

Where did the story come from?

The research was carried out by Prof. Bengt Arnetz and colleagues of Wayne State University and Uppsala University, and Foundation IT’IS, USA, and Karolinska Institutet, Sweden. The study was funded by the Mobile Manufacturers Forum. The study was published in the peer-reviewed scientific journal: Progress In Electromagnetics Research Symposium (PIERS) Online.

What kind of scientific study was this?

This was a double blind, experimental, laboratory study designed to investigate further the relationship between exposure to radio waves during mobile use and a variety of self-reported symptoms.

The volunteers were 71 men and women aged 18-45. Thirty-eight of the volunteers had symptoms that they attributed to mobile use (problems with mental thinking, stress hormones, performance and sleep).The other 33 volunteers reported no “mobile-related symptoms”. Both the symptomatic and non-symptomatic subjects reported using their mobiles daily and the amount ranged from five minutes to three hours per day.

All the participants took part in two laboratory experiments, the order of which was randomly set by the researchers. During these two experiments, the volunteers received exposure to radio waves or “sham” exposure. The participants did not know which exposure they were receiving. During the true exposure, the participants were exposed to 884 MHz GSM wireless communication signals; this included both periods of discontinuous transmission (to imitate a mobile that was switched on but not being used) and non-discontinuous transmission (to imitate exposure during speaking on a mobile), to the left half of the head only. The researchers stated the exposure to be “consistent with worse case exposure occurring in real-life situations, but with extended duration”. Both sessions lasted for three hours duration.

While the sessions were taking place, the participants carried out performance and memory tests, reported their mood state and scored any symptoms they experienced on a seven-point scale from “not at all” to “a high degree”. Following the sessions, they slept in a sleep laboratory during which their brain activity was monitored by electroencephalogram (EEG).

The experiments were carried out in a shielded laboratory. Before the experiments began, background radio and electromagnetic frequency recordings of the environment were made to ensure that they were within protocol. It was also forbidden to use mobiles in the area around the exposure laboratories.

What were the results of the study?

The researchers found that, following radiofrequency exposure, the participants took an average of about six minutes longer to reach the deep stage of sleep than when they had received the sham exposure. They also spent an average eight minutes less time in the deepest “stage four” sleep.

Reports of headache were greater during radio wave exposure than during “sham” exposure in the subjects who had previously not reported mobile-related symptoms. However, in those who were symptomatic, there was no difference in the reporting of headache between the two exposures. Neither group was able to detect with accuracy whether they were being exposed to the true radio waves or to sham exposure. The journal paper did not report any results of their performance, memory, or mood tests.

What interpretations did the researchers draw from these results?

The authors concluded that “radiofrequency exposure under these conditions is associated with adverse effects on sleep quality within certain sleep stages”.

They also say that these links between radiofrequency exposure and self-reported symptoms are “pertinent to the current discussions of possible effects from mobile phone generated radiofrequency exposure”.

What does the NHS Knowledge Service make of this study?

This study will probably fuel further debate about the existence of harms associated with prolonged mobile use. However, there are several important points to consider when interpreting this report:

  • The radiofrequency exposures given during this experiment were extreme and, as the authors acknowledge, “consistent with worst case exposure occurring in real-life situations, but with extended duration”.  Therefore, the exposures are not directly comparable with real life situations.
  • Although the participants had reduced deep sleep following exposure to radiofrequencies compared to sham, it is important to note that this was not sleep during normal conditions. It was conducted in a laboratory, not following the natural pattern of waking and sleep and, as the authors term it, was “induced sleep”. There are no further details in the report on this.
  • This was a relatively small study in only 71 people and this may not accurately reflect what would happen in the general populace. The results would have to be confirmed in a much larger study before we can draw any conclusions about the effects of radio waves on sleep.
  • The fact that the participants who already had symptoms that they attributed to mobile use, experienced the same degree of headache during both radiofrequency and sham exposure, suggests that they may have been expecting to experience symptoms during the experiment, or that their headache was related to other causes. However, the non-symptomatic subjects did report more headaches during radiofrequency exposure, and this requires further investigation.

There is no suggestion from this experiment that radio waves cause confusion or have any harmful affects upon mood, concentration or personality, as the newspapers have interpreted.

NHS Attribution