# Exploring the potential effects of different frequencies of flashing light stimulation on alleviating mental fatigue: a behavioral and EEG study

## TL;DR

This study explores how flashing lights at different frequencies can reduce mental fatigue and improve alertness, using behavioral and EEG data.

## Contribution

The study introduces broader frequency-band flashing light stimulation as a novel method to alleviate mental fatigue, beyond single-frequency approaches.

## Key findings

- 20–30 Hz flashing light stimulation significantly improved reaction times and reduced subjective fatigue.
- EEG analysis showed normalization of alpha-to-beta power ratio and complexity in frontal and occipital regions.
- 40 Hz and 60 Hz stimulations had more complex and varied effects on brain activity and fatigue.

## Abstract

Mental fatigue, characterized by reduced attention and prolonged reaction times, is a critical issue in professions requiring high vigilance, such as driving and air traffic control. It contributes to numerous accidents each year. At the neural level, mental fatigue is associated with alterations in cortical oscillatory activity, particularly in the alpha and beta frequency bands, which reflect changes in alertness and cognitive engagement. While flashing light stimulation has emerged as a promising non-invasive approach to enhance alertness by modulating brain oscillations, existing research has predominantly focused on single-frequency stimulation. The potential benefits of broader frequency-band stimulation remain largely unexplored.

This study aimed to explore the effects of different frequencies of flashing light stimulation on alleviating mental fatigue. A total of 32 right-handed male participants were recruited. A 2-back task was used to establish a mental fatigue model, and mental fatigue was assessed using the Psychomotor Vigilance Task (PVT) and EEG data. Participants were divided into a control group and three experimental groups, receiving flashing light stimulation at 20–30 Hz, 40 Hz, and 60 Hz for 3 minutes. EEG data were analyzed using power spectral density and Lempel-Ziv complexity (LZC) metrics to assess the effects of stimulation on brain activity.

The 20–30 Hz frequency-band light stimulation significantly improved reaction times and subjective fatigue ratings. EEG analysis showed normalization (decrease) of the alpha-to-beta power ratio and LZC, particularly in the frontal and occipital regions. In contrast, the 40 Hz and 60 Hz groups exhibited different EEG modulation patterns, and their effects on fatigue were more complex.

Flashing light stimulation at 20–30 Hz frequencies effectively alleviates mental fatigue and enhances alertness. These findings suggest that broader frequency-band light stimulation could offer a more effective method for reducing mental fatigue compared to single-frequency stimulation. Further research is needed to investigate the optimal parameters for light stimulation and its potential applications in clinical and everyday settings.