Relationship between Vigilance Level as Physiological Index of Alpha Waves and Postural Sway

Abstract

The alpha attenuation test (AAT) has been developed within the last few years as a method to measure vigilance levels using electroencephalogram (EEG) . However, measuring vigilance levels by the AAT is complicated and time-consuming, as electrodes need to be attached to the subject. The present study examined the influence of changes in the number of alpha waves on vigilance level and attempted to find a relationship between postural sway and vigilance level. If a mutual correlation could be found between vigilance level and postural sway, measurement of vigilance level could be simplified. The results showed that postural sway increases as vigilance level decreases. In particular, head sway and alpha waves displayed a significant correlation. We thus expect that vigilance levels will be able to be measured using head sway as a substitute for EEG in the future.