Influence of Rotating Shift Work on Visual Reaction Time and Visual Evoked Potential

Abstract

Background: The present day life style is changing the circadian rhythm of the body especially in rotating night shift workers. The impact of this prolongs their reaction time. Night shift also interferes with the circadian variation of pupil size which may affect the visual evoked potential. Aim: To compare the visual reaction time, visual evoked potential (VEP) in rotating night shift workers & day workers and also to correlate the changes in visual reaction time with visual evoked potential. Materials and Methods: Forty healthy male security guards & staff (25 – 35 y) who did rotating night shifts at least for six months & 40 d workers (25 – 35 y) who did not do night shift in last two years were involved in the study. Visual reaction time and the latency & amplitude of VEP were recorded. Result: Kolmogorov- Smirnov test for normalcy showed the latencies & amplitude of VEP to be normally distributed. Student’s unpaired t test showed significant difference (p<0.05) in the visual time and in the latencies of VEP between night shift & day workers. There was no significant difference in the amplitude of VEP. Conclusion: Night shift workers who are prone to circadian rhythm alteration will have prolonged visual reaction time & visual evoked potential abnormalities. Implementation of Bright Light Therapy would be beneficial to the night shift worker.

Keywords

• circadian rhythm
• shift workers
• visual reaction time
• visual evoked potential