Mobile Phone Talk-Mode Signal Delays Sleep Onset

TitleMobile Phone Talk-Mode Signal Delays Sleep Onset
Publication TypeConference Paper
Year of Publication2007
AuthorsHung, CS, Anderson, C, Horne, JA, McEvoy, P
Conference Name21st Annual Meeting of the Associated Professional Sleep Societies
Conference Start Date09/06/2007
PublisherAssociated Professional Sleep Societies
Conference LocationMinneapolis, Minnesota, USA
ISSN Number0161-8105

Introduction: Mobile phone signals are microwaves, pulse-modulated at extremely low-frequency (ELF), which differ between `talk´ and `listen´ modes, as do their respective specific absorption rates (SARs). Previous studies have shown ELF components are more important than microwave carriers for sleep/wake EEG effects, but no sleep study has differentiated these two modes.
Methods: We used a standard GSM 900 MHz mobile phone, operating at 12.5% (23dBm) of maximum power and controlled by a base-station simulator with a test SIM card. ELF components and SARs of talkmode are: 8, 217/1736 Hz with SAR=0.133 mW/g and for listen-mode: 2, 8, 217/1736 Hz with SAR=0.015 mW/g (for a 10g averaged tissue). 10 right-handed healthy young men (mean age: 22±2.7y), sleep restricted to 6h, were exposed (blind) to talk, listen and sham (nil signal) modes at weekly intervals. Ss lay in a sound-proof bedroom, with a thermally insulated phone attached beside the right ear and a silent signal generated for 30 min, starting at 13:30h. Ss remained silent and stared at a wall marker. Bipolar EEGs were recorded continuously, and subjective ratings of sleepiness obtained every 3 min (only during exposure). After exposure the phone and base-station were switched off, the bedroom darkened, and a 90-min sleep opportunity followed. Results are focused on sleep-onset using : i) visually scored latency to onset of stage 2 sleep, ii) EEG power spectral analysis.
Results: Post-exposure, sleep latency after talk-mode was markedly and significantly delayed beyond listen- and sham-modes. This condition effect was also evident in 1-4Hz EEG left frontal power across time, and 12-16Hz EEG right frontal power was different between talk and listen modes during waking before the first appearance of stage 1 sleep. There was no condition effect for subjective sleepiness.
Conclusion: Talk mode shows an alerting effect. It is possible that 2, 8, 217 Hz modulation may differentially affect sleep-onset.

Full Text