A randomized, double-blind, crossover study of acute low-level night-time road traffic noise: effects on vascular function, sleep, and proteomic signatures in healthy adults.
Hahad O, Foos P, et al. • Cardiovascular research • 2026
Acute exposure to night-time road traffic noise leads to measurable changes in cardiovascular health parameters in healthy adults, with effects linked to activation of molecular pathways of immune signalling and interindividual biological susceptibility.
Key Findings
Results
Night-time road traffic noise caused a dose-dependent, statistically significant decrease in endothelial function as measured by flow-mediated dilation (FMD).
FMD decreased from 9.35% in the control condition to 8.19% after 30 noise events (Δ = 1.16%, P = 0.005) and to 7.73% after 60 noise events (Δ = 1.63%, P < 0.0001).
The study used a randomized, double-blind, crossover design with 74 healthy participants exposed to three overnight conditions.
Control condition had an LAeq of 30.70 dB, 30 noise events had LAeq 41.36 dB, and 60 noise events had LAeq 44.13 dB, with peak levels approximately 60 dB.
FMD was assessed the morning after each overnight exposure condition.
The dose-dependent pattern of FMD impairment suggests a graded vascular response to increasing noise event frequency.
Results
Vitamin C administration attenuated the noise-induced reduction in endothelial function, implicating oxidative stress as a contributing mechanism.
The strongest FMD improvement by vitamin C occurred in the 60-event condition (Δ = 1.02%).
A subgroup of participants received vitamin C to assess oxidative stress involvement.
The vitamin C effect suggests that reactive oxygen species (oxidative stress) play a role in noise-induced endothelial dysfunction.
This finding provides mechanistic evidence linking noise exposure to oxidative stress pathways in humans.
Results
Night-time road traffic noise increased heart rate and the frequency of nocturnal heart rate peaks.
Mean heart rate increased with a mean difference of Δ = 1.23 bpm (P = 0.04).
The odds of post-noise heart rate peaks were significantly elevated, with an odds ratio of 2.42 (95% confidence interval 2.07–2.83).
Heart rate was measured as part of secondary endpoints including blood pressure and electrocardiogram monitoring.
Results
Self-reported sleep quality and restfulness were significantly impaired across all dimensions following noise exposure.
Sleep quality was assessed using questionnaires as a secondary endpoint.
Impairment was observed across all dimensions of self-reported sleep quality and restfulness.
This was consistent across the noise exposure conditions (30 and 60 events) compared to the control condition.
Subjective sleep impairment was noted even at relatively low average sound pressure levels (LAeq ~41–44 dB).
Results
Clinical chemistry blood parameters did not change significantly following noise exposure.
Standard clinical blood chemistry markers were measured as part of the secondary endpoints.
No statistically significant changes were observed in clinical chemistry parameters after any noise condition.
This suggests that acute single-night noise exposure effects are detectable at the vascular and proteomic levels before conventional blood biomarkers are altered.
This contrasts with the significant changes observed in FMD, heart rate, and proteomics.
Results
Proteomic analysis revealed noise-associated changes in interleukin signalling and chemotaxis pathways, particularly in participants with the strongest FMD impairments.
Targeted proteomic analysis was performed using Olink panels.
Noise-associated proteomic changes were identified in interleukin signalling and chemotaxis pathways.
Changes were most pronounced in participants classified as 'responders' (those with the strongest FMD impairments) versus 'non-responders'.
Plasma proteome changes were correlated to FMD changes, highlighting interindividual biological susceptibility to noise.
These findings link noise-induced cardiovascular effects to immune signalling activation.
Methods
The study design used a randomized, double-blind, crossover framework to investigate acute low-level night-time road traffic noise in healthy adults.
74 healthy participants were enrolled and exposed to three overnight conditions in crossover fashion.
The three conditions were: control (no noise, LAeq 30.70 dB), 30 recorded road traffic noise events (LAeq 41.36 dB), and 60 recorded road traffic noise events (LAeq 44.13 dB).
Peak noise levels were approximately 60 dB across both noise conditions.
The primary endpoint was endothelial function assessed by FMD the morning after each night.
Secondary endpoints included sleep quality questionnaires, blood pressure, heart rate, ECG, and targeted proteomic analysis.
What This Means
This research suggests that even relatively quiet road traffic noise at night — averaging around 41–44 decibels with occasional peaks near 60 decibels — can measurably harm blood vessel function and heart rate in healthy adults after just a single night of exposure. Researchers had 74 healthy people sleep under three different conditions (quiet control night, a night with 30 traffic noise events, and a night with 60 traffic noise events) in a carefully controlled crossover experiment. They found that the more noise events people were exposed to, the worse their blood vessel function was the next morning, and that their hearts were more likely to experience spikes in heart rate during the noisy nights. People also reported sleeping worse and feeling less rested after noisy nights.
This research suggests that the mechanism behind these effects involves oxidative stress — a type of cellular damage caused by unstable molecules — because giving participants vitamin C (an antioxidant) partially reversed the blood vessel impairment. Additionally, a protein analysis of participants' blood revealed changes in immune signalling pathways, especially in people whose blood vessel function was most affected by the noise. Interestingly, standard blood tests showed no significant changes, meaning that these more sensitive measures (blood vessel function tests and protein analysis) detected harm that routine medical tests would have missed.
This research suggests that noise pollution, even at levels considered relatively low by regulatory standards, poses a real biological risk to cardiovascular health. The findings are particularly relevant because they were observed in healthy people after just one night, raising questions about what cumulative, long-term exposure to traffic noise might do to health over months or years. The observation that some people's blood vessels responded much more strongly than others points to the possibility that certain individuals may be biologically more vulnerable to noise-related cardiovascular harm.
Hahad O, Foos P, Hübner J, Große-Dresselhaus C, Schmidt F, Ostad M, et al.. (2026). A randomized, double-blind, crossover study of acute low-level night-time road traffic noise: effects on vascular function, sleep, and proteomic signatures in healthy adults.. Cardiovascular research. https://doi.org/10.1093/cvr/cvag028