International Journal of Hygiene and Environmental Health
Effect of nocturnal road traffic noise exposure and annoyance on objective and subjective sleep quality
Introduction
Environmental noise is a consequence of modern lifestyle and its impacts on health are of growing concern. In urban environments, road traffic noise is the most widespread source of noise exposure. It has been estimated that about 50% of the EU-population is exposed to A-weighted day-evening-night equivalent sound pressure level (Lden) of road traffic noise levels that exceed 55 dB(A) and 16% are exposed to nocturnal road traffic noise above 55 dB(A) (WHO, 2011).
Exposure to traffic noise has been shown to disrupt sleep, both in laboratory and field studies, leading to noise-related sleep disturbances (Öhrström et al., 1990, Miedema and Vos, 2007, Aasvang et al., 2008, de Kluizenaar et al., 2009, Aasvang et al., 2011, Basner et al., 2011, Brink, 2011). According to the WHO, sleep disturbances constitute the most serious consequence of environmental noise in western European countries (WHO, 2011). Sleep disturbances can lead to serious long term health effects, and there is increasing evidence from epidemiological studies that long-term noise exposure leads to cardiovascular diseases (Huss et al., 2010, Babisch et al., 1999, Babisch, 2011, Sorensen et al., 2011, WHO, 2011, Dratva et al., 2012, Sorensen et al., 2012).
It has been hypothesized that the effect of noise exposure might be mediated through annoyance rather than through a direct exposure effect, and that noise annoyance is a better marker of stress-related noise impacts than objective noise as it includes the perception and disturbance of the exposed individual (Nivison and Endresen, 1993, Marquis-Favre et al., 2005, Jakovljevic et al., 2006, Dratva et al., 2010, Birk et al., 2011). It is even recommended by the EU Directive 2002/49/EC that environmental noise exposure is evaluated by means of the estimated noise annoyance (European Union, 2002). Noise annoyance was shown to be associated with health related quality of life (Dratva et al., 2010). It is less clear, however, to which extent noise exposure affects sleep quality directly, independent of perceived annoyance due to traffic.
The aim of this study was to investigate the effect of both, road traffic noise exposure and annoyance on subjective, self-reported as well as objective sleep quality measures, assessed by actigraphy. In order to study the effects of noise exposure on sleep without the influence of noise annoyance we put a special focus on individuals who were not annoyed by road traffic noise.
Section snippets
Main study: participants and questionnaire
The present study was conducted within the framework of the QUALIFEX study (health related quality of life and radio frequency electromagnetic field (RF-EMF) exposure: prospective cohort study), a study with a focus on health effects due to environmental exposures, in particular RF-EMF exposure (Frei et al., 2010, Mohler et al., 2010, Röösli et al., 2010, Frei et al., 2012). The recruitment procedure including detailed definitions of sleep parameters is described in detail elsewhere (Mohler et
Study participants
In the main study, 1375 participants filled in the baseline and 1122 the follow-up questionnaire, leading to a total of 2497 observations. Due to night shift work and consumption of sleeping pills, 285 observations were excluded. Additional observations were deleted due to missing information on noise exposure (1 observation) or annoyance (14 observations). In total, 2197 observations from 1256 individuals were available. In the nested diary study sleeping data for 1666 nights were collected
Discussion
Our results indicate that sleep efficiency measured by actigraphy and self-reported sleep disturbances are affected by nocturnal exposure to road traffic noise. Interestingly, in the diary study objectively measured sleep efficiency was more strongly associated with modeled noise exposure than with self-reported annoyance. Most strikingly, the effect of nocturnal traffic noise on sleep efficiency was more pronounced in persons not annoyed compared to the rest of the sample.
Strengths and limitations
Our study was performed in a large random population sample and we have collected objective sleep quality data from more than 1500 nights which has been rarely done before. We were able to adjust our analyses for a large range of potential risk factors, including socio-demographic and lifestyle characteristics, and to perform sub analyses in subjects not annoyed by road traffic noise.
Another strength of this study was that we collected information on both subjective and objective sleep and
Interpretation
Our results are in line with epidemiological and laboratory studies that have found effects of traffic noise exposure and noise annoyance on different sleep parameters (de Kluizenaar et al., 2009, Jakovljevic et al., 2009, Pirrera et al., 2010). It is noteworthy that we found an interesting pattern for these two types of exposure measures. Annoyance was strongly related to self-reported sleep measures in the main study and to a lesser extent also in the diary study. However, it was not related
Conclusions
This study indicates that objective sleep quality is impaired by road traffic noise exposure independently of perceived annoyance, whereas the association between self-reported sleep quality is mediated by noise annoyance. The WHO recommends that night noise levels do not exceed 40 dB(A) (WHO, 2009). Our data support this threshold.
Conflict of interest
The authors declare no conflict of interest.
Funding
The study was funded by the Swiss National Science Foundation (Grant 405740–113595). Martin Röösli is supported by the Swiss School of Public Health+ (SSPH+).
Acknowledgements
We thank Fabian Trees from the Swiss Federal Statistical Office for providing the geographical coordinates of the study participants and the statistical department of Basel for providing the addresses of the study participants. We thank Dominik Aebi from the Federal Office for the Environment and Priska Plüss from the Basel-City Office for the Environment and Energy for providing road traffic noise data for study participants from the canton of Basel-Country and Basel-City, respectively. Many
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