Nighttime environmental noise affects sleep quality. However, the effects of daytime occupational noise remain unclear.
A quasiexperiment involved 48 participants who had been employed for at least 6 months in two hospital cafeterias. The participants were randomly designated to be assessed on high- and low-noise workdays for 8 hours or low- and high-noise workdays, separated by a washout period of 14 days. Subsequently, pure tone audiometry, autonomic nervous system (ANS) function tests, serum cortisol tests, and polysomnography were conducted.
For the 40 participants in the study, the 8-hour time-weighted average of personal noise exposed on high- and low-noise workdays was 76.8 dBA, respectively. Participants with higher personal noise exposure during the day were found to have a lower percentage of slow wave sleep and lower sleep efficiency. In addition, after work, personal noise exposure was revealed to be related to increased serum cortisol levels, and sympathetic activity as measured by low frequency/high frequency and blood pressures by cold pressor test.
Daytime occupational noise exposure had sustained effects on nighttime sleep quality, specifically on slow wave sleep and sleep efficiency. These disturbances could be partially explained by post-shift elevated cortisol and ANS activity. The psychosocial and metabolic consequences of poorer sleep quality induced by occupational noise exposure warrant further investigation.