A person in the measurement chamber wearing the electrodes cap that registers brain electrical activity. Credit: INERIS / Project GOLIAT

A new GOLIAT study led by researchers from INERIS reports no measurable biological effects of short-term exposure to 5G signals on either stress responses or brain electrical activity in healthy adults.

The results of the study were disclosed in two different papers published in Environmental Research. These are the first coordinated human laboratory studies to assess potential acute effects of exposure to the highest frequency band of 5G under conditions that resemble real environmental levels.

Both studies examined exposure to real 5G signals and found no changes in physiological stress markers or in the patterns of electrical activity that the brain naturally generates at rest. The results indicate that brief exposure to 5G signals similar to those found in the environment did not alter the body’s stress response or the brain’s typical electrical rhythms.

The studies shared a triple-blind, randomized design, in which participants, experimenters and data analysts did not know whether a real or sham (placebo) exposure was being administered. All sessions took place in an electromagnetically shielded room to avoid interference. Participants were seated 120 cm from a horn antenna emitting a 5G New Radio signal at 26 GHz, with intensities of 2 V/m at the head and 1 V/m at the torso—levels corresponding to the highest values measured in real outdoor environments by the French national frequency authority.

Study 1 and study 2 were carried out at the same time with the same protocol: each volunteer completed one session with real exposure and one with sham exposure, each lasting around one hour, including 26.5 minutes of exposure. During these sessions, researchers collected saliva samples to analyze two validated stress biomarkers (cortisol and alpha-amylase) and recorded the brain’s electrical activity using electroencephalography.

This approach allowed the team to assess both physiological stress responses and potential changes in the brain’s natural electrical patterns under identical exposure conditions.

No changes detected in brain electrical activity

Using electroencephalography, the researchers monitored the brain’s electrical oscillations across all major frequency bands—delta, theta, alpha and beta—which correspond to different natural rhythms of brain activity. These range from the slow waves linked to deep rest (delta) to the faster waves associated with alertness and mental activity (beta). Across all bands, and at all time points before, during and after exposure, the researchers found no differences between the real and sham exposure sessions.

Short-term exposure also did not affect the body’s physiological stress response. Cortisol and alpha-amylase, two widely used indicators of stress and autonomic nervous system activation, remained stable across all sampling points. Therefore, the researchers did not find evidence that exposure to 5G signals at environmental levels triggers acute biological changes related to stress.

Why study 26 GHz?

The 5G technology uses different frequency bands. Although the 3.5 GHz had an earlier and wider deployment, the study focuses on the 26 GHz band, which is being introduced to support faster data transmission.

"We focused on 26 GHz because there were very few studies examining its potential impact on humans," explains Lisa Michelant, researcher at INERIS and first author of both papers. "It is a new frequency for public mobile communication, and its physical behavior—such as limited penetration into the skin—differs from that of lower-frequency 4G or 5G signals."

According to Brahim Selmaoui, researcher at INERIS and senior author of the research, "These findings are consistent with previous scientific evidence showing no acute biological effects at commonly encountered radiofrequency exposure levels. While more research is still needed on long-term and repeated exposures, our results provide reassuring data for this new 5G band and contribute to ongoing safety assessments by international health authorities."

More information: Lisa Michelant et al, Millimeter-wave high frequency 5G (26 GHz) electromagnetic fields do not modulate human brain electrical activity, Environmental Research (2026). DOI: 10.1016/j.envres.2025.123349

Lisa Michelant et al, No measurable impact of acute 26 GHz 5G exposure on salivary stress markers in healthy adults, Environmental Research (2026). DOI: 10.1016/j.envres.2025.123439

Citation: Controlled laboratory study finds no evidence of stress or brain activity changes related to 5G exposure (2025, December 10) retrieved 10 December 2025 from https://medicalxpress.com/news/2025-12-laboratory-evidence-stress-brain-5g.html

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