The chronic exposure to radiofrequency electromagnetic fields modified the thermopreferendum during sleep in juvenile rats
Résumé
Sleep disturbances by radiofrequency electromagnetic fields (RF-EMF) emitted by mobile phone base stations type GSM are not well-known. In a previous study, we pointed out that most effects of RF-EMF on sleep were dependent on the thermal environment, suggesting that RF-EMF exposure may modify sleep through interactions with thermoregulatory processes. In the present study, juvenile rats exposed to RF-EMF were allowed to choose their thermal environment corresponding to the thermopreferendum. Sleep was scored as comfort criteria. Six wistar rats (3 weeks-old) exposed to RF-EMF (900 MHz, 1 V/m) during 5 weeks were compared to a non-exposed group (n=4). One week after surgery, sleep was measured (wireless) during the day when animals were allowed to move freely between 3 similar communicated rooms which differ according to their ambient temperatures (24 °C, 28 °C and 31 °C). Wakefulness (W), Slow Wave (SWS) and Paradoxical Sleep (PS) were scored at 10 second-periods. The time spent in each room, the total durations of sleep stages, the mean durations of episodes and their frequencies were tested using Mann-Whitney and Wilcoxon. Exposed rats preferred to sleep at 31 °C whereas the controls preferred 28 °C. At 31 °C, the total time sleep was increased (+139 min and +103 min compared to 24 °C and 28 °C respectively, p<0.05) as a result of longer total durations of SWS (compared to 24 °C: +107 min, p<0.05) and of PS (compared to 24 °C and 28 °C: +10 min and +7 min respectively, p<0.05). The frequencies of SWS and PS episodes also increased at 31°C compared to 24 °C (SWS: +167 % and PS : +111 %, p<0.05). In sleeping rats, the thermopreferedum was increased by chronic exposure to RF-EMF. The increased sleep duration suggests that the animals exposed to RF-EMF may develop behavioral responses to prevent energy expenditure.