Effects of 2.45 GHz Wi-Fi exposure on sleep-dependent memory consolidation

J Sleep Res. 2020 Nov 9;e13224. doi: 10.1111/jsr.13224. Online ahead of print.

Abstract

Studies have reported that exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile telephony might affect specific sleep features. Possible effects of RF-EMF emitted by Wi-Fi networks on sleep-dependent memory consolidation processes have not been investigated so far. The present study explored the impact of an all-night Wi-Fi (2.45 GHz) exposure on sleep-dependent memory consolidation and its associated physiological correlates. Thirty young males (mean ± standard deviation [SD]: 24.1 ± 2.9 years) participated in this double-blind, randomized, sham-controlled crossover study. Participants spent five nights in the laboratory. The first night was an adaptation/screening night. The second and fourth nights were baseline nights, each followed consecutively by an experimental night with either Wi-Fi (maximum: psSAR10g = <25 mW/kg; 6 min average: <6.4 mW/kg) or sham exposure. Declarative, emotional and procedural memory performances were measured using a word pair, a sequential finger tapping and a face recognition task, respectively. Furthermore, learning-associated brain activity parameters (power spectra for slow oscillations and in the spindle frequency range) were analysed. Although emotional and procedural memory were not affected by RF-EMF exposure, overnight improvement in the declarative task was significantly better in the Wi-Fi condition. However, none of the post-learning sleep-specific parameters was affected by exposure. Thus, the significant effect of Wi-Fi exposure on declarative memory observed at the behavioural level was not supported by results at the physiological level. Due to these inconsistencies, this result could also be a random finding.

Keywords: EEG power; declarative memory; emotional memory; procedural memory; sleep spindles; slow oscillations.