Auditive beta stimulation as a countermeasure against driver fatigue

Abstract

Objective Fatigue in road traffic can occur after long driving times or during night-time driving and can lead to a dangerous decrease in vigilance or microsleep. As a countermeasure, the effectiveness of brain stimulation by means of frequency-modified music is investigated. Small frequency shifts between two different sounds simultaneously perceived by both ears (e.g. 400 and 418 Hz) stimulate the brain to increase activity in the stimulated range (e.g. 18 Hz). Methods The effects of acoustic brain entrainment (ABE) in the EEG beta range (12–20 Hz) were compared to placebo during day and night driving (n = 40 each) in 80 subjects. The effects were examined at the subjective (Karolinska Sleepiness Scale, KSS), physiological (EEG) and performance level (test battery for attention testing, TAP). The test drive took place on the motorway. Sequence of events with measurement times: Preparation in the laboratory (60 min; TAP & KSS), driving (90 min day/ 180 min night; KSS every 30 min), beta/placebo stimulation while driving (20 min), rest (20 min; TAP & KSS), driving (60 min; KSS every 30 min), end of driving (40 min; TAP & KSS). EEG was recorded continuously (Fz, Cz, Pz, C3, C4) and analyzed for 10 min time windows. Results The subjective fatigue rating in the KSS decreased significantly after ABE compared to placebo. This was still significant about 100 minutes after stimulation. The ABE led to a significant increase in EEG beta activity compared to placebo. This was still significant about 80 minutes after stimulation. Furthermore, the ABE led to a significant decrease in theta activity compared to placebo. This was still significant about 70 minutes after stimulation and was more pronounced during daytime driving. Faster reaction times were observed for the ABE compared to the placebo condition during day and night driving. The faster reaction times were partly significant for the ABE still 80 minutes after stimulation. Conclusion Positive effects of ABE during driving could be demonstrated on the subjective, physiological and performance level. The effect was more pronounced during the day than at night. No negative side effects of Beta Stimulation were observed. The stimulation in the beta frequency range led to an increase of beta activity in the EEG.