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Epidemiological study (observational study)

Exposure to Radiofrequency Electromagnetic Fields and Sleep Quality: A Prospective Cohort Study.

Published in: PLoS One 2012; 7 (5): e37455

Aim of study (acc. to author)

A prospective cohort study was conducted in Switzerland to investigate whether sleep quality is affected by mobile phone use or by other radiofrequency electromagnetic field sources in the everyday environment. Furthermore, the consistency of the results should be checked in a nested sleep study with measured exposure and measured sleep behavior data.

Further details

Sleep disturbances were determined by means of four standardized questions (difficulty in falling asleep, fitful sleep, waking phases during night, and waking too early in the morning) from the Swiss Health Survey 2007 and daytime sleepiness by seven items of the Epworth Sleepiness Scale.
In the nested sleep study including 119 study participants, exposure to radiofrequency electromagnetic field was measured in the bedroom and data on sleep behavior was collected by means of actigraphy (monitoring sleep-wake cycles) during two weeks.
Further results of the QUALIFEX study are published in Röösli et al. (2010), Mohler et al. (2010) and Frei et al. (2012) .

Endpoint/type of risk estimation

Type of risk estimation:
  • prevalence

Exposure

Assessment

Exposure groups

Reference group 1 total everyday life exposure: < median
Group 2 total everyday life exposure: 50. - 90. percentile
Group 3 total everyday life exposure: > 90. percentile
Reference group 4 night-time exposure: < median
Group 5 night-time exposure: 50. - 90. percentile
Group 6 night-time exposure: > 90. percentile
Reference group 7 residential exposure to fixed site transmitters: < median
Group 8 residential exposure to fixed site transmitters: 50. - 90. percentile
Group 9 residential exposure to fixed site transmitters: > 90. percentile
Reference group 10 mobile phone use: < median
Group 11 mobile phone use: 50. - 90. percentile
Group 12 mobile phone use: > 90. percentile
Reference group 13 mobile phone use based on operator data: < median
Group 14 mobile phone use based on operator data: 50. - 90. percentile
Group 15 mobile phone use based on operator data: > 90. percentile
Reference group 16 cordless phone use: < median
Group 17 cordless phone use: 50. - 90. percentile
Group 18 cordless phone use: > 90. percentile

Population

  • Group:
    • men
    • women
  • Age: 30–60 years
  • Characteristics: Swiss residents or people living in Switzerland for at least 5 years
  • Observation period: May 2008, follow-up in May 2009
  • Study location: Switzerland (region of Basel)
  • Data source: QUALIFEX study
  • Exclusion criteria: regular usage of sleeping pills, night shift working

Study size

Eligible 3,763
Participants 1,375
Evaluable 955
Other: 119 participants in the nested sleep study
Statistical analysis method:
  • logistic regression
( adjustment: )

Conclusion (acc. to author)

No association between exposure to radiofrequency electromagnetic fields in an everyday environment and self-reported sleep disturbances or excessive daytime sleepiness was found during an exposure period of one year. These results were confirmed in the nested sleep study with objectively recorded exposure and measured sleep behavior data.
The authors concluded that they found no evidence for adverse effects on sleep quality from radiofrequency electromagnetic field exposure in an everyday environment.

Study funded by

  • Swiss National Science Foundation (SNF)
  • Swiss School of Public Health + (SSPH+), Switzerland

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