Road traffic noise and sleep disturbances in an urban population: cross–sectional study

TLDR: Noise annoyance, subjective noise sensitivity, and neuroticism were significantly correlated with difficulties with falling asleep, time needed to fall asleep, poorer sleep quality, tiredness after sleep, and use of sleeping pills.

Abstract: Noise is one of the major environmental hazards of the modern world, originating from a wide variety of sources, including traffic (air, road, or rail), industrial facilities, or social activities. About 40% of the population in the European Union are exposed to road traffic noise with an equivalent sound pressure level (Leq) exceeding 55 dB(A) at daytime, whereas 20% are exposed to levels above 65 dB(A). Noise pollution is a major public health problem in developing countries as well. It is caused mainly by road traffic; the 24-hour Leq can reach even 75-80 dB(A) along the main roads. More than 30% of Europeans are exposed to Leq exceeding 55 dB(A) at night, which may cause sleep disturbances (1). Systematic noise measurements in Serbia were performed in four cities with a population over 250 000. The results of follow-up measurements in Belgrade over 30 years showed that outdoor noise levels exceeded the allowed limits on 23 out of 27 measuring sites for 11-16 dB during day and 10-14 dB during night (2). In contrast to some other environmental problems, noise pollution continues to increase, followed by an increasing number of complaints from the exposed residents. The adverse health effects of community noise pose a serious public health problem. They include hearing impairment, interference with speech communication, disturbance of rest and sleep, psychological and performance effects, effects on one’s behavior, and subjective annoyance and interference with intended activities. Furthermore, noise has socio-cultural, esthetic, and economic effects. The estimated social costs for all noise nuisances are around 2.1% of the gross national product in industrialized countries, with about 0.2% attributable to productivity losses and 1.9% to decreases in property values (3). Healthy sleep is a prerequisite for good physiological and mental functioning. However, disturbed sleep includes biological responses that may have numerous adverse effects on health and well-being, from difficulties with falling asleep, alterations of sleep stages, and awakenings to increased blood pressure and cardiac arrhythmia (4). The pathophysiological basis for a noise-sleep relation may be the stimulation of hypothalamus-pituitary-adrenal axis, adrenal medulla, and sympathetic nervous system with a subsequent release of “stress hormones,” ie, adrenaline, noradrenaline, and cortisone (5). These biological responses might have long-term health implications including chronic fatigue syndrome, lower work productivity, increased proneness to accidents, and disturbances of blood pressure and coronary circulation. Substantial individual differences in neuroendocrine, immune, and behavioral responses to noise indicate that the level of noise itself may not be of primary importance. A close relation between arousal level and personality traits, such as introversion, neuroticism, and subjective noise sensitivity, can explain these differences (6,7). However, it is still unclear how important these personality characteristics are for the occurrence of sleep disturbances. The aim of this study was to explore the relationship between extroversion-introversion, neuroticism, and subjective noise sensitivity as personality traits and sleep disturbances caused by traffic noise. We expected personalities characterized by higher levels of introversion, neuroticism, and subjective noise sensitivity to be more prone to noise-disturbed sleep.