# Pink noise reduces impact of traffic noise on sleep and the blood metabolome: a cross-over pilot study

## TL;DR

Playing pink noise during sleep reduces the negative effects of traffic noise on sleep and blood metabolites, which could help prevent long-term health issues.

## Contribution

This study is the first to show that pink noise can mitigate both sleep disruption and metabolic changes caused by traffic noise.

## Key findings

- Traffic noise causes acute sleep fragmentation and increases levels of leucine, lactic acid, and acetone in the blood.
- Pink noise reduces the physiological and metabolic effects of traffic noise during sleep.
- Sleep macrostructure remains largely unaffected despite noise-induced disruptions.

## Abstract

Epidemiological studies show associations between chronic noise exposure and disease, but the biological pathways remain poorly understood. In this explorative pilot study, we investigate the mechanisms that may link sleep disruption by environmental noise with disease, and the efficacy of a non-pharmacological intervention to mitigate these effects.

We conducted a cross-over trial (ClinicalTrials.gov: NCT05319262; 2022-03-09) where N = 12 healthy individuals slept for five consecutive nights in acoustically isolated bedrooms. Nights included one familiarisation night; one quiet baseline night; one night with road, rail and air traffic noise of levels 45-65 dB LAS,max; one night with continuous 45 dB broadband pink noise; and one night with both traffic noise and pink noise. Sleep was measured with polysomnography. Perceived sleep quality and recouperation were measured with morning questionnaires. Daily blood samples were collected for metabolomics analysis.

Here we show that discrete traffic noise events induced acute elevations of the odds ratio product, indicating acute sleep fragmentation, even while total sleep time and overall sleep macrostructure were preserved. Traffic noise is further associated with significant elevations in concentrations of leucine, lactic acid, and acetone relative to quiet control. Sleep and metabolic disturbances by traffic noise are attenuated when pink noise is played continuously throughout the night.

Noise-induced sleep fragmentation is followed by changes in metabolic processes that in the long-term may be precursors for cardiometabolic disorders. Masking of traffic noise by continuous, neutral sound may mitigate acute physiological sleep disturbance and downstream metabolic effects. These results should be interpreted cautiously, given the limited sample size and subject homogeneity.

This study explored how environmental noise at night might affect health and whether a simple sound-based intervention could help. Twelve healthy adults slept under different sound conditions, including quiet, traffic noise, and continuous low volume noise, termed “pink noise”. Researchers measured sleep quality and changes in certain compounds in the blood. Traffic noise caused brief disruptions in sleep and altered levels of certain compounds linked to energy use. However, during continuous playback of pink noise, these negative effects were reduced. These findings suggest that even when total sleep time is not affected, noise can disturb the body’s physiology in ways that may affect long-term health. Continuous neutral sounds like pink noise could help protect sleep and well-being in noisy environments.

Vincens et al. investigate how traffic noise and masking pink noise impact physiological sleep, cognition, and metabolic blood biomarkers. Traffic noise acutely fragments sleep even while total sleep time is preserved, and is followed by metabolic disturbances, the effects of which are attenuated by continuous pink noise.