Lowden A, Akerstedt T, Ingre M, Wiholm C, Hillert L, Kuster N, Nilsson JP, Arnetz B. Sleep after mobile phone exposure in subjects with mobile phone-related symptoms. Bioelectromagnetics. Sep 20, 2010. Ahead of print.
Results from population surveys indicate that 1.5-10% of the population suffer from non-specific symptoms that they attribute to exposure to electromagnetic fields (EMFs), in particular to exposure from mobile phones. This self-reported electromagnetic hypersensitivity is associated with sleep complaints. Previous studies have shown that exposure to EMFs prior to sleep or during sleep may lead to changes in electrical brain activity detected by electroencephalography (EEG).
The objective was to investigate whether exposure to radiofrequency (RF) EMFs from a mobile phone in the evening would have any effect on subsequent night sleep, and whether the effect (if any) is more pronounced in subjects with self-reported electromagnetic hypersensitivity.
A total of 48 subjects (27 female and 21 male, mean age 28 years, age range 18-44 years) underwent two exposure sessions for 3 hours (7:30 pm-10:30 pm) prior to sleep. One was real exposure to 884 MHz RF signal (head only, time-averaged 10 g psSAR of 1.4 W/kg) and the other - sham exposure. The study was double blind; neither the subjects nor the examiners were aware of the type of exposure applied. Of the 48 subjects, 23 (15 females, mean age 27 years) were “EMF sensitive” and 25 (12 females, mean age 29 years) were “non-sensitive”. Self-rated sleepiness and full-night electrophysiological recordings were analyzed.
There was no effect of exposure or EMF sensitivity on self-rated sleepiness. Exposure to RF was associated with a significant increase in Stage 2 sleep minutes (8.3 min or 4% on average), and a significant decrease in Stage 4 and Stage 3+4 sleep minutes (9.5 min or 12% on average). The latency to stage 3 (from sleep onset) was significantly increased (4.8 min on average). Analysis of EEG have shown that after RF exposure the power during the first 30 min of Stage 2 sleep was significantly elevated in the frequency ranges 0.5-1.5 and 5.75-10.5 Hz. During the full first hour of Stage 2 sleep the power was elevated in the frequency range 7.5-11.75 Hz, during the second hour of Stage 2 sleep - in the range 4.75-8.25 Hz. There were no power changes during the third hour of Stage 2 sleep. There was no significant effect of self-reported EMF sensitivity on the studied sleep parameters.
Interpretation and Conclusion
The authors have concluded that the results of this study support data from other studies “regarding RF-induced changes in sleep EEG parameters, but these effects do not seem to be different between groups with and without symptoms that relate to their mobile phone use in everyday life.”