Sleep disturbance caused by meaningful sounds and the effect of background noise

Abstract: This study compared the effects of road, rail, and aircraft noise and tested the applicability of the equivalent noise level for the evaluation of sleep disturbances. Sixteen women and 16 men (19–28 years) slept during 3 consecutive weeks in the laboratory. Eight persons slept in quiet throughout. Twenty-four persons were exposed to road, rail, or aircraft noise with weekly permuted changes. Each week consisted of a random sequence of a quiet night (32 dBA) and 3 nights with equivalent noise levels of 39, 44, and 50 dBA and maximum levels of 50–62, 56–68, and 62–74 dBA, respectively. The polysomnogram was recorded during all nights, sleep quality was assessed and performance tests were completed in the morning. Subjectively evaluated sleep quality decreased and reaction time increased gradually with noise levels, whereas most physiological variables revealed the same reactions to both the lower and considerably stronger reactions to the highest noise load. Aircraft noise, rail and road traffic noise caused similar after-effects but physiological sleep parameters were most severely affected by rail noise. The equivalent noise level seems to be a suitable predictor for subjectively evaluated sleep quality but not for physiological sleep disturbances.

Abstract: A bedside personalized ventilation (PV) was proposed to be used in the bedroom. An experiment with human subjects was performed to ascertain whether there are any negative consequences if applying this PV to sleeping people. Thirty-six subjects slept in the thermal neutral bedrooms with or without the bedside PV for a whole night in a winter season, while their physiological parameters and body movement were continuously measured. The autonomic cardiac measurements showed that the power of very low frequency (VLF) component and the low/high frequency (LF/HF) ratio of the subjects significantly decreased when the PV was turned on, although no significant change in sleep quality (measured with questionnaire and actigraphy) was found. They perceived to be cooler and their skin temperature decreased when they slept with PV, even if the supplying air temperature of PV was slightly higher than that of the background environment. The present study implies that the bedside PV could be used as a potential ventilation principle for sleeping people.

Abstract: This article reviews the literature about the effects of specific non-traffic-related ambient noise sources on sleep that appeared in the last two decades. Although everybody is faced with noise of non-traffic and non-industry origin (e.g. sounds made by neighbors, talk, laughter, music, slamming doors, structural equipment, ventilation, heat pumps, noise from animals, barking dogs, outdoor events etc.), little scientific knowledge exists about its effects on sleep. The findings of the present extensive literature search and review are as follows: Only a small number of surveys, laboratory and field studies about mainly neighborhood, leisure and animal noise have been carried out. Most of them indicate that ambient noise has some effect on human sleep. However, a quantitative meta-analysis and comparison is not possible due to the small number of studies available and at times large differences in quality.

Abstract: In the present study, the effects of different noise combinations on sleep were assessed in two contexts, with a single noise source and with combined noise sources. Road traffic noise, and construction or movie noise combined with road traffic noise were used as the single noise source and the combined noise sources, respectively. When the sound pressure level of road traffic noise was kept constant, levels of the construction and movie noise were changed. Twenty participants were followed for approximately 2 weeks, during which their sleep was evaluated using a questionnaire, including questions on sleeping behavior, premature awakening, and subjective responses. The results showed that the combined noise sources including construction noise decreased the number of participants who fell asleep within an hour and increased the number that were awakened prematurely compared to the effects of road traffic noise combined with movie noise. However, similar tendencies were observed while evaluating sleep quality, sleep disturbance, and annoyance.

Abstract: The effects of sound on man are reviewed with emphasis on the physiological reaction mechanisms and the ultimate stress reaction. It is seen that energy related noise levels are poor predictors for the reactions in man as noise is always interpreted in the central nervous system, generating secondary and tertiary reactions that are not controlled by the brain cortex. The stimulation of these reaction pathways in acute situations lead to involuntary reflexes and feelings of fright and despair. In chronic exposure situations a give-up stage may develop with reduced corporal and mental functions. In the acoustical panorama peak level noises usually cause the most pronounced effects as they stimulate reactions of fear and flight. The practical consequences of these reaction patterns in terms of prevention are discussed.

Abstract: The effects of road traffic noise on sleep were studied in the laboratory using nine young male adults (aged 20–26). The subjects were exposed to noise with different temporal characteristics: (i) continuous traffic noise of 36 dB(A) or 45 dB(A), (ii) intermittent noise of 50 truck passages with L pmax = 45 dB(A) ( L eq = 29 dB(A)) or L pmax = 55 dB(A) ( L eq = 36 dB(A)), and (iii) a combination of continuous (45 dB(A)) and intermittent ( L pmax = 55 dB(A)) traffic noise. For one noise condition (intermittent 55 dB(A)) the effect of the use of ear plugs was also studied. The intermittent noise of L pmax = 45 dB(A) caused transitions towards lighter sleep, whereas 55 dB(A) was needed to induce awakening effects. It could be shown that the probability for arousal reactions depends on the emergence of the noise peaks from the background, rather than the absolute noise peak level. Continuous traffic noise of 45 dB(A) caused REM sleep deficits, while intermittent traffic noise of L pmax = 45 dB(A) caused stage III+IV deficits. The night with ear plugs was virtually undisturbed. After nights with REM sleep deficits the subjective sleep quality was rated lower and mood was influenced adversely. For the types of exposure used in the present investigation L eq alone is not an adequate descriptor of the noise dose, relating to the sleep disturbances observed. From the present experiment, together with other existing data, it might be concluded that the WHO recommendation of L eq = 35 dB(A) is adequate, but should be supplemented with a maximum noise level, as expressed for example in L pmax or L I , that should not be exceeded.

Abstract: The permanently open auditory channel and the ability of the brain to process incoming acoustical stimuli even while asleep and to respond adequately is the essential precondition for noise-induced sleep disturbances which are regarded as the most deleterious effects of noise. In the past, research was mainly focused on the detection and description of the various effects of noise, on the influence of personal and environmental factors, on the determination of dose ­response relations and the definition of critical noise loads, above which noise becomes intolerable. These limits are, however, as yet only tentative or applicable for a very few situations and need to be verified or revised. The present paper is focused on the priorities for future research. These are in particular 1) the causal linkage between environmental noise, primary and secondary effects on the one hand and the hypothesized contribution to multifactorial chronic diseases, to chronic annoyance, and to permanent behavioral alterations on the other hand, 2) the identification of the causes for the great discrepancies between the small effects determined in the field and the large responses recorded in the laboratory, 3) temporal aspects such as sleep at unusual times (day sleep after nightshifts), definition of night-time and day-time, 4) the significance of the shoulder hours for subsequent sleep, 5) the individual vulnerability, 6) the accumulation of data from different studies.

Abstract: The aim of study reported here was to elucidate the importance of number of noise events with a high maximum noise level for sleep disturbance effects in terms of body movements, subjective sleep quality and performance. The noise exposure consisted of 4, 8, 16 and 64 passages from heavy vehicles. Twenty-eight subjects between 20 and 29 years of age were exposed to either 50 or 60 dB(A) maximum noise levels. The result showed that sleep quality decreased with increased number of noise events at 60 dB(A) maximum noise level. At 16 noise events/night the decrease in sleep quality was significant (−29%). At 50 dB(A) there was no relation between the number of noise events and sleep quality. The sleep quality was effected at 64 noise events, primarily by a prolonged time to fall asleep. Performance on a three-choice reaction time test (FV) was decreased after 60 dB(A) as compared to 50 dB(A). It is suggested that to protect people from sleep disturbance effects from road traffic noise, it is necessary to consider the number of vehicles of a certain maximum noise level.

Abstract: The paper updates the knowledge on noise-induced sleep disturbances. If people do not habituate completely to their usual acoustic environment, health disorders can be expected in the long run. For the determination of admissible limits, continuous and intermittent noise must be considered separately. The latter causes larger reactions and is (in this context) defined by a distance of more than 10 dBA between the equivalent sound pressure level and the maximum levels. The admissible risk for intermittent noise is determined by a curve which relates the maximum levels to the number of the single noise events. The critical load for continuous noise is suggested as 40 dBA indoors. Additionally, critical situations and critical groups are considered (e.g. shiftwork, time of night, illness, aged people). Finally, various preventive measures and their (presumed) benefits are discussed (e.g. sleeping pills, double glazing, speed limits, traffic diversion).