Sleep EEG Spectra After Exposure To Mobile Phone 'Talk' And 'Listen' Mode Signals: Pulse-Modulation Frequency Dependent Effects

TitleSleep EEG Spectra After Exposure To Mobile Phone 'Talk' And 'Listen' Mode Signals: Pulse-Modulation Frequency Dependent Effects
Publication TypeConference Paper
Year of Publication2008
AuthorsHung, CS, Anderson, C, Horne, JA, McEvoy, P
Conference Name22nd Annual Meeting of the Associated Professional Sleep Societies
Conference Start Date07/06/2008
Conference LocationBaltimore, Maryland, USA
ISSN Number0161-8105

Introduction: Mobile phone ‘talk’ and ‘listen’ mode signals share the same pulse modulation frequency at 8 and 217 Hz while listen mode has an extra 2-Hz modulation. Our previous study showed talk-mode to delay sleep onset (Hung et al., 2007). Here we reported an extended analysis of the same study with EEG spectra during stage 2 (S2) and slow-wave sleep (SWS).
Methods: 90-min sleep EEGs, early afternoon, were obtained from 10 right-handed healthy young men (sleep restricted to 6h), after a 30-min exposure to a standard GSM 900 MHz mobile phone emissions at talk, listen and sham (nil signal) modes during prior waking, given weekly. Mean S2 and SWS EEG power (log-transformed values) across 1-16 Hz range per recording were calculated in 1-Hz bins at bipolar derivations (F3-C3, C3-P3, P3-O1, F4-C4, C4-P4, P4-O2), by averaging individual time series, aligned with respect to the onset of S2 and SWS. Condition effects on: (i) S2 and SWS EEG power at single Hz and (ii) SWS EEG combined 1-4 Hz power were assessed by one-way ANOVAs for repeated measurements. We also investigated effects on the modulation of EEG spindles (14-16 Hz power) by 2-4 Hz power during SWS, using linear regression coefficients between these two EEG dynamics and compared three modes.
Results: Compared with sham, both talk and listen modes reduced S2 EEG spindles (talk: 12-15 Hz, listen: 13-16 Hz) power but this effect of listen-mode was less distributed (only seen at C4-P4). During SWS, EEG 1-4 Hz power was not different from sham mode in either condition however listen mode significantly enhanced: SWS EEG 11-13 Hz power at F4-C4; 12-14 Hz at C3-P3, compared with sham mode. Talk mode showed no effect on SWS EEG spectra. Regression coefficients between EEG power at 2-4 Hz and 14-16 Hz during SWS over the central/parietal/occipital regions showed significanttly higher values fter listen-mode exposure.
Conclusion: Compared with talk mode, listen mode increased S2 and SWS EEG spindle frequency activities, without significant changes in sleep propensity and SWS intensity. It suggests the extra 2-Hz modulation has different sleep effects from 8 and 217-Hz modulation.

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