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| Year : 2002
| Volume
: 5 | Issue : 17 | Page
: 35-45 |
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| Stress Hormone Changes in Persons exposed to Simulated Night Noise |
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C Maschke1, J Harder2, H Ising2, K Hecht3, W Thierfelder4
1 Robert Koch-Institute, Federal Institute for Infectious and Noninfectious Diseases, Section: Environmental related disorders, Berlin, Germany
2 Federal Environmental Agency, Institute for Water, Soil and Air Hygiene, Berlin, Germany
3 Institute of Psycho-Social Health Berlin, Germany
4 Robert Koch-Institute, Federal Institute for Infectious and Noninfectious Diseases, Section: Epidemiology and health-reporting, Berlin, Germany
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The results of earlier studies attribute acute stress reactions to nocturnal aircraft noise, but do not contain detailed information on the adaptive and habituation processes during the exposure. This question was followed up with an experimental longitudinal study at Hamburg's Fiihlsbiittel airport. The test persons were exposed to nocturnal electroacoustically simulated aircraft noise in their apartments. Recorded among other things was the personal health condition, cortisol excretion collected through the night and daily collected subjective data. After the initial cortisol reaction (increasing in the first days) the course of cortisol excretion is not uniform.
The results suggest that adaptation to nocturnal aircraft noise is specific to the sex. Beside these sexually specific differences there are considerable individual differences both for women and men. We found three fundamental adaptation types in agreement with results of animal experiments.
From a preventive medical point of view two of the adaptation types, i.e. increasing cortisol excretion and decreasing cortisol excretion, are accompanied with health hazards. The increasing cortisol excretion exceeds the normal medical range in the process of adaptation. The decreasing cortisol level can be identified as "protective inhibition". The majority of the men can be classified in the first mentioned adaptation type. From this knowledge it can be concluded that noise-induced health risk for men is to be estimated as essentially higher than for women. Keywords: Nocturnal aircraft noise, cortisol excretion, adaptation, health hazard
How to cite this article:
Maschke C, Harder J, Ising H, Hecht K, Thierfelder W. Stress Hormone Changes in Persons exposed to Simulated Night Noise. Noise Health 2002;5:35-45 |
| Introduction | |  |
As with every stress-trigger, noise induced a non-specific response profile consisting primarily of neural and humoral processes. The nerve impulses induced by the noise find their way via the auditory cortex just as the amygdala to the hypothalamus-hypophysial system (Spreng 2000a). By these way, noise can cause stress reactions in the body, during which adrenaline, noradrenaline and cortisol are excreted (e.g. Ising 2000). The intensity of the stress reaction was moderated e.g. by predisposition, experience and self-control patterns. The stress hormones stimulate the affected organs and among other things influence the cardiovascular system, metabolism and the blood lipids (Spreng 2000b).
The biological purpose of the stress reaction is the mobilisation of energy to prepare the body for fight, flight or defeat. During sleep the organism reacts especially sensitively to noise exposure. This was for example shown in a field study on the effect of nocturnal aircraft noise around Berlin's Tegel airport (Maschke et al.,1995). The test persons slept at home and collected the urine from the night for two weeks: in the first week under control conditions and in the second week with additional nocturnal noise in their bedrooms (16 or 64 flyovers with maximum sound levels of 55 or 65 dB(A)). Analysed among other things, were the stress hormones in their urine excretion.
A significant increase of the adrenaline excretion was observed in the first two noisier nights, but two or three nights after the start of the additional flight noise, the high adrenaline secretion decreased to the pre-exposure values. Parallel to the normalisation of adrenaline a significant increase of cortisol was observed (see Ising 2000).
The results of this field study demonstrated stress reactions caused by 4 nights under flight noise exposure but did not contain information on chronic effects of noise. Therefore we carried out a 6 week noise exposure experiment in order to observe the adaptive and habituation processes.
| Methods | | |
A total of 16 residents living near the airport (Hamburg-Fuhlsbuttel) were studied over a period of 40 nights. The test persons slept in their own apartments and were exposed to additional nocturnal aircraft noise. This was possible, because at Hamburg-Fuhlsbuttel airport there are nearly no starts or landings during the night. For the first three days there was no additional nocturnal flight noise. During the further 37 nights, 32 takeoffs and landings with sound levels of L max = 65 dB(A) were simulated electro-acoustically each night using a computer controlled system. The simulation began at 23 p.m. and stopped at 6 a.m.. During this time the flight events were spread stochastically. The 8 hour L eq of all the events was 42dB(A) and the duration of each noise signal was between 30s and 65s. The test persons got a small expenditure-compensation of 500 German Mark.
The night urine excretion was collected each morning and analysed for the amount of free cortisol in it (enzyme immuno assay method). Moreover the amount of adrenaline and noradrenaline were quantified with a HPLCmethod.
Furthermore, subjective data were collected daily via questionnaire; one at the beginning of the study, one each morning and one questionnaire each evening, before the test person went to bed. The questionnaire at the beginning of the study included for example the test persons age, habits, medical history, illness and employment. The morning questionnaire contained questions about the sleeping quality and impairment. The evening questionnaire contained for example questions about daytime encumbrance and the consumption of alcohol.
At the beginning and at the end of the study a stress regulation test according to Balzer and Hecht (1989, 1998) was conducted. During the stress-diagnostic test, the persons were subjected to a short acoustic stressor (1 min) during a relaxation phase. The dermal skin-resistance is analysed before, during and after the irritation. The test provides information on the regular condition of the test person in connection with a blood pressure relaxation test (Hecht et al. 1998). An unstable regulation can be interpreted as a precursor stage to illness (premorbid phase). The fundamental steps of the stress-diagnostic test are represented in the [Figure1].
| Results | | |
The first important medical result of the study is the observation of strong rhythmic fluctuations of the cortisol values especially in the second part of the investigation. An autocorrelation shows that a clear weekly-rhythm (circa-septan rhythm) exists and the analysis of variance 1 confirm significant differences within the nights (p = 0,016) with two significant trendcomponents. A weekly rhythm (p < 0,001) and a trend-component 2nd order (p = 0,033). The remainders of variance is no longer significant (p = 0,302). It is therefore to be assumed no further trend-components.
The averaged excretion of cortisol are shown in the first figure for all subjects (dotted line) and for the usable subjects (whole line). Included in the figures are both the measured cortisol excretion and the trend (2 nd order). The weekly rhythm is indicated. For preventive medical assessment the normal medical range has been drawn in. During the first three days of the study no nocturnal flight noise was played back; these days are labelled as shaded areas in the figures. One subject was excluded because of a pathological high cortisol excretion over the whole study including the first nights without noise exposure (range 117 to 450µg/24h).
Another person could not considered in the analysis of variance because of lacking usable values for some days. The problem was strong stress independently from the nightly noise exposure.
In the first half of the investigation the weeklyrhythm is probably disturbed because of the beginning of the aircraft noise simulation. In the second half, the weekly-rhythm is well to be recognized. The time series uncovered a great problem. Cortisol values collected under the same treatment but on different weekdays cannot be compared meaningfully with each other. The existing results suggest that cortisol values should be collected for at least one week.
The second important result of the study is the observation of a sexual specific reaction of the cortisol excretion under night time noise exposure. The averaged excretion of cortisol is shown for men and women separately in [Figure - 3],[Figure - 4].
The female test persons show a cortisol excretion trend that remains on average constant. The average cortisol excretion of the women exhibit slight weekly rhythms especially in the second part of the investigation. The initial reaction to the start of the additional nocturnal aircraft noise is marked; the cortisol value remains within the normal medical range, which is indicated with the two broken horizontal lines. No relation between cortisol excretion and the menstruation cycle was found.
The male test persons exhibit on average a reaction pattern, in which an increasing cortisol excretion trend (sensitizing phase) follows a phase of decreasing cortisol excretion (contraregulation).
Weekly-rhythms are also observable for men, but the variations of the cortisol excretion within a week are considerably higher as with the women. The initial reaction is stronger and exceeds slightly the normal medical range. Both the initial reaction and the cortisol secretion trend is different for men and women. The analysis of variance of the weekly mean values shows a significant interaction between week and sex (p = 0,002).
Independent of sex, the highest excretion within the initial reaction is measurable around the third noisy night, but the average amplitude for men is significant higher than for women (p = 0,038). Under chronic noise, the cortisol excretion trend for men increased after a period of decreasing trend in the initial weeks, whereas the cortisol secretion trend for women is stable. Beside being sexually specific the cortisol secretion displays the weekly rhythm with higher amplitudes for men.
The results suggest that adaptation to nocturnal aircraft noise is sexually specific. On the other hand there are distinct individual differences within the men and women. The differences are mainly explicable by three adaptation types acquired from cluster analysis. These adaptation types agree with earlier results from animal experiments (Nitschkow 1968) as well as with epidemiological studies (Ising 2000) and can be represented by the following figures. The most common regulation type (RT) is indicated in the figure (stable/ unstable).
The first adaptation type [6 subjects] shows a reaction pattern with an increasing cortisol excretion trend in the second half of the experiment. The temporary course is similar to that of the men, but at the end of the experiment the cortisol excretion exceeds the normal medical range. The initial cortisol reaction to the nocturnal aircraft noise was pronounced but did not exceed the normal medical range. The weekly-rhythm is clearly recognizable. In the last 10 days of the experiment, the weekly maximum for cortisol exceeded the normal range.
The second adaptation type [4 subjects] shows a pronounced initial reaction followed by a decreasing cortisol excretion trend. The initial reaction is strong and exceeds clearly the normal medical range. The averaged cortisol values of the first days correspond approximately to the results of the mentioned Berlin field study. After the initial reaction the deviations from the calculated trend are slight. A clear weeklyrhythm is not recognizable.
The third adaptation type [5 subjects] shows a cortisol excretion trend that barely changes. The initial reaction is slight and the weekly rhythm of cortisol excretion predominates in the second half of the study.
The analysis of variance shows significant differences within the nights (p = 0,004) and a significant interaction between group and nights (p = 0,019). As well, the interaction is significant between the adaptation-types and the amount of transgressions of the normal medical range per week (p = 0,044). The results suggest that the endocrine reaction, as part of the adaptation, can be subdivided into three subgroups with increasing, decreasing or stable trend of excretion. For the most subjects, 5 weeks nocturnal flight noise leads to a dysregulation of the neuro-endocrine parameters.
In addition, the time-series gives an explanation why simple cross-sectional studies are often unfit to identify noise induced effects. If the averaged effects are analysed, a computation of increasing and decreasing reactions was made. The averaged effect is slight and may be positive or negative.
| Subjective Data and Adaptation | | |
[Figure - 8],[Figure - 9],[Figure - 10] display the course of the subjective 'well-being' factor for the three adaptation types, acquired by factor analysis from the questionnaire data. Included in the figures are both the calculated 'well-being' and the trend (2 nd order). Lower factor values indicate a reduced well-being.
The daily answers show that well-being declines during the study for the three cortisol types. The course of well-being however, exhibits clear differences between the reaction types.
For adaptation type 1 (cortisol trend increasing), the feeling of comfort declines continuously after approximately 2 weeks of the nocturnal aircraft noise. The initial reaction is moderate and the maximum is time delayed being observed during the third night with noise. No clear chrono-biological legality can be recognized for the deviations.
For adaptation type 2 (cortisol trend decreasing), there is a continuous decline of well-being to be observed immediately after the beginning of the nocturnal noise exposure. The initial reaction is strong and the maximum is time delayed and observed in the third night with additional noise. Well-being is already reduced at the start of the study. The deviations are presumably accidental.
For adaptation type 3 (cortisol trend remaining constant) a slight fall in the well-being trend is to be observed during the first half of the study. In the second half the well-being trend remains nearly constant. The initial reaction is moderate and the magnitude is time delayed and observed on the third night with noise. The deviations are presumably accidental:
The good agreement with the endocrine reaction shows that a long-term decreasing of subjective well-being level induced by nocturnal noise may be a simple indicator of health hazards. Thereby it must be considered that large deviations, presumably caused by individual events, superimpose strongly on the well-being level. Short-term elevation of the well-being allows no valid conclusions on the health effect of noise.
| Stress Regulation | | |
A broader differentiation of adaptation types was possible by the stress-diagnostic test, which was applied both at the beginning as well as at the end of the study.
The results of the test allow the conclusion that a close link exists between the reaction type of the cortisol excretion and the results of the stress regulation test. The results can be summarised by:
All test persons with either an increasing cortisol excretion (adaptation type 1), or with a decreasing cortisol excretion (adaptation type 2), already showed signs of an unstable regulation.
The test persons with unchanged cortisol excretion trend (adaptation type 3) possessed normal regulation (with 1 exception). An increasing cortisol excretion or a decreasing cortisol excretion were only observed in persons who had to be classified as not having a stable regulation even before the noise exposure. However and contrary to adaptation type 1, for all subjects with a decreasing cortisol excretion (adaptation type 2) there is a further noise reduced constriction of the regulation observed after exposure (2nd regulation test). This reaction type can be identified as "protective inhibition" and probably represents the transition from the resistance phase into the exhaustion phase (Selye). The adaptation type 2 must also be classified as a health hazard.
Back to the sexual differences. The differences between women and men - mentioned at the beginning - can be explained with the three adaptation types.
The adaptation types 1 are in the majority the men. Most women belong to adaptation type 3. From this knowledge it can be concluded that the noise induced health risk for men is to be estimated as essentially higher than for women.
| Discussion | | |
The urine excretion during the night was corrected for 8h and then extrapolated to 24h by multiplying with the factor 3. The 24h cortisol excretion can be compared with the medical normal range. This normal range depends on the analysing method. For the used method (enzyme immuno assay method from Immunotech) the range is from 26 to 80µg/24h. In the literature a range of 20 to 100µg/24hr is indicated. We used the wider range making this a conservative method.
The main result of this experiment was the observation that more than half of the test persons did not habituate to night-time noise with a comparatively low Lmax = 65dB(A) and an L eq of 42 dB(A) during 8 night hours.
A comparison of this level with the extremely high noise levels which are necessary to cause direct cortisol increases in active persons (see Ising 2000) shows that in sleeping persons much lower noise levels are sufficient to trigger psychophysical reactions.
However, it was unexpected that in several persons during the five weeks of exposure the normal range of cortisol was already exceeded. On the other hand a cortisol dysregulation towards hypocortisolism was detected in some of the test persons. This development may be explained by the adaptation model of Selye (1956).
Since both types of dysregulation may lead to serious health problems (Oelkers, 2000) further investigation is necessary to quantify the percentage of the population, which could develop hyper- or hypocortisolsm under chronic environmental noise exposure. This percentage might be high, since 15% - 20% of the European population are exposed to traffic noise levels with Leq >_ 55 dB(A) at night time or 65 dB(A) during the day outside of their homes. Since with windows open the indoor levels will be about 10 to 15dB below the outside levels, the indoor levels of about 50 to 70 million people in Europe are comparable to the noise exposure in this experiment or the Berlin road traffic field study (Ising et al 1998) Chronic hypercortisolism was found in a considerable number of the test persons in these studies.
In the Berlin study (see Ising 2000) as well as in this experiment the women showed significant lower noise-related cortisol increases as compared with men.
The question as to whether cortisol increases will remain during prolonged stress was answered by Larina et al (1997), who monitored the cortisol excretion of test persons during more than 20 weeks of simulated space flight conditions.
Cortisol increased to nearly double the preexperimental values and remained elevated until the end of the experiment.
The long term health consequences of hypercortisolism have been described in the literature and include arteriosclerosis, steroid diabetes, immunosuppression and gastrointestinal ulcera (Sapolsky, 1986; Spreng 2000b).
| Summary | | |
Under persistent nocturnal aircraft noise, adaptation procedures are noted which are interpreted as the resistance phase in terms of the general adaptation syndrome (Selye). The neuroendocrine reaction as part of the adaptation can be subdivided into three subgroups with either increasing, decreasing or stable trend of cortisol excretion. The adaptation types, decreasing cortisol trend as well as increasing cortisol trend are connected with health hazards. The increasing cortisol excretion exceeds the normal medical range in the process of adaptation and the decreasing cortisol level can be identified as a "protective inhibition". Both adaptation types were only observed in persons who had to be classified as "no longer healthy" even before the noise exposure.
The adaptation is sexually specific. The adaptation types with recorded increasing or decreasing cortisol trend, are in the majority for the men. Most women belong to the adaptation type with a stable cortisol trend (regulated). From this knowledge it can be concluded that the noise induced health risk for men can be estimated essentially higher than for women.
Regarding the long time series, the subjective well-being (investigated in the evening) may also be an easy indicator of health hazards. Short-term elevation of the well-being allows no meaningful conclusions on the health effect of noise.
In addition, the results show presumably why simple cross-sectional studies are often unfit to identify noise induced health effects. If averaged health effects have been analysed, a computation of increasing and decreasing outcomes is often made, so that the averaged outcome is accordingly slight. The results uncovered still another problem. For some outcomes strong rhythmic deviations are to be expected. That means, outcomes collected on different weekdays can not be compared meaningfully with each other. The observed circaseptan rhythm suggest that the cortisol excretion has to be monitored for at least one week.[16]
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| 16. | Spreng, M. (1996): Verwaltungsrechtsstreit Flughafen Hahn. Gutachterliche Stellungnahme zur Frage 3a des Fragenkatalogs vom 31.05.1996. Erlangen |
Correspondence Address:
C Maschke
Müller-BBM GmbH, Robert-Koch-Str. 11, 82152, Planegg bei München
Germany
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 12537833 
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10], [Figure - 11] |
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