Night-exposure to noise induces hearing loss more than day exposure

Abstract

Objective: It was reported that exposure to high noise levels at night would induce more hearing loss in mice than exposure in the day. The present study aims to test this finding in human.

Materials and methods: Eighty-four subjects were included in this study. They were males, working at textile factories. According to the type of working shifts of the workers, the study group was subdivided into two equal groups; (i) Day group: including those who worked only in day shifts through all of their employment, (ii) Day and night group: including those who worked in alternating shifts; day shift for a week followed by night shift for another week.

Results: The day and night group had significantly higher (worse) thresholds at frequencies 3, 4, 6 kHz. Fourteen subjects (17%) in the present study had bilateral normal hearing sensitivity; 12 subjects (14%) in the day group and 2 subjects (2%) in the Day and night group.

Conclusions: Alternating night and day noise exposure proved to be more insulting to the cochlea and resulted in a more pronounced hearing loss when compared to day only-noise exposure.

Keywords:

• Hearing conservation
• circadian rhythm
• night exposure to noise
• protection against noise

Disclosure statement

No potential conflict of interest was reported by the authors.