COGNITIVE REACTION TIME PERFORMANCE AND SUBJECTIVE DROWSINESS: A CRITICAL EVALUATION OF THE EFFECT OF WHOLE-BODY VIBRATIONS

Abstract

It is believed that exposure to whole-body vibration (WBV) may increase seated occupant drowsiness, and seated occupant drowsiness may contribute to vehicular accidents. Previous studies on driver comfort have indicated that long-term exposure to WBV may have an adverse effect on musculoskeletal disorders. However, the effects of WBV on seated occupants’ drowsiness have been less rigorously studied. Thus, this study aims to investigate the association between exposure to WBV and drowsiness level. Laboratory experiments were designed and involved eighteen healthy male volunteers. Volunteers were exposed to random gaussian vibration for 20-minutes with the frequency between 1-15Hz. The transmitted vibration magnitude was adjusted for each volunteer to become 0.2ms-2 for low vibration magnitude and 0.4ms2 for medium vibration magnitude. Volunteers’ vigilance was measured by the Psychomotor Vigilance Task (PVT) before and after the vibration exposure. The analyses revealed a substantial drop in volunteers’ vigilance level after exposure to vibration and the effect was more pronounced in high vibration amplitude 0.4 ms-2. These findings suggested that exposure to vibration even as low as 20-minutes may attribute to the reduction of alertness level.