Thermopreferendum during sleep is modified by radiofrequency electromagnetic radiation exposure during development

Objectives : sleep disturbances by GSM-type radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phone base stations are not well-established. In a previous study, we pointed out that most effects of RF-EMR were dependent on the thermal environment, suggesting that RF-EMR exposure may modify sleep through interactions with thermoregulatory processes. In the present study, juvenile rats exposed to RF-EMR were allowed to choose their thermal environment corresponding to the 'thermopreferendum'. Methods : 6 Wistar rats (three weeks-old) exposed to RF-EMR during five weeks were compared to a non-exposed control group (n=4). One week after surgery, sleep was measured (wireless) when animals were allowed to move freely between three similar communicating rooms which differed according to ambient temperature (24, 28 and 31+-1 °C). Wakefulness (W), Slow Wave (SWS) and Paradoxical Sleep (PS) were scored at 10 second-periods. The total durations of sleep stages, the mean durations and the frequencies of the episodes were tested with ANOVA. Results : exposed rats preferred to sleep at 31 °C whereas the controls preferred 28°C. The choice of 31 °C induced longer total time sleep (+139 and +103 min compared to 24 and 28 °C respectively) as a result of longer total durations of SWS (compared to 24 °C : +107.4 min) and of PS (compared to 24 and 28 °C: +9 and +7 min respectively). Conclusion : thermopreferendum during sleep was increased when exposed to RF-EMR suggesting modifications of the peripheral thermosensitivity. This observation and the longer sleep duration suggest that the RF-exposed group may develop behavioral responses to prevent energy expenditure.