P013 The Effect of Noise Exposure during Sleep on the Cortisol Awakening Response

Abstract Introduction Environmental noise could negatively impact the sleep and well-being of nearby residents. This study tested for overnight noise exposure effects on the cortisol awakening response (CAR), a potential marker of noise-related stress responses, and for differences in CAR and hair cortisol between different prior noise exposure groups. Methods A randomised controlled laboratory trial was conducted in 68 individuals from four groups; including WFN-exposed residents n=14 with and n=18 without WFN-related complaints, n=18 quiet rural control and n=18 urban traffic-noise exposed residents. Across six nights, after an initial adaptation night, participants were exposed in random order to different noise conditions, which included intermittent WFN and road traffic noise (RTN), WFN at average exposure levels throughout wake, sleep or both and a quiet control night. Salivary CAR responses were evaluated from 5 serial saliva samples collected following awakening. Hair cortisol levels were also collected. Mixed effects models were used to examine group and night effects on CAR and group effects on hair cortisol. Results There was a significant main effect of condition on CAR (p=0.038), but no significant pairwise differences between the control night and noise exposure nights, and no further differences between nights or groups on CAR or hair cortisol concentrations. Conclusions Acute in-laboratory noise-related sleep disturbance at the levels used in this study do not appear to alter acute cortisol awakening responses. A better understanding of chronic noise exposure effects and stress responses is important to help clarify and mitigate potential environmental noise exposure effects on nearby residents.