Pulsed radio-frequency electromagnetic fields: dose-dependent effects on sleep, the sleep EEG and cognitive performance

SUMMARY To establish a dose–response relationship between the strength of electromagnetic fields(EMF) and previously reported effects on the brain, we investigated the influence ofEMF exposure by varying the signal intensity in three experimental sessions. The headof 15 healthy male subjects was unilaterally exposed for 30 min prior to sleep to a pulse-modulated EMF (GSM handset like signal) with a 10 g-averaged peak spatial specificabsorption rate of (1) 0.2 W kg –1 , (2) 5 W kg –1 , or (3) sham exposed in a double-blind,crossover design. During exposure, subjects performed two series of three computerizedcognitive tasks, each presented in a fixed order [simple reaction time task, two-choicereaction time task (CRT), 1-, 2-, 3-back task]. Immediately after exposure, night-timesleep was polysomnographically recorded for 8 h. Sleep architecture was not affected byEMF exposure. Analysis of the sleep electroencephalogram (EEG) revealed a dose-dependent increase of power in the spindle frequency range in non-REM sleep.Reaction speed decelerated with increasing field intensity in the 1-back task, whileaccuracy in the CRT and N-back task were not affected in a dose-dependent manner. Insummary, this study reveals first indications of a dose–response relationship betweenEMF field intensity and its effects on brain physiology as demonstrated by changes inthe sleep EEG and in cognitive performance.keywords cellular phone, dose–response relationship, electroencephalogram