Psychophysiological stress effects from the combination of night-shift work and noise.

The influence of night-shift work and noise on arousal and stress reactions have, to date, been investigated separately. The aim of this study was to compare their psychophysiological effects in combination. Twenty-four male student subjects continuously performed ten hours of visual display tasks per 24 h under highly controlled conditions for either five consecutive day or night shifts, followed by two days of rest. Each group worked in conditions of simulated traffic noise, at either 80 or 50 dB(A). Urinary catecholamines, electrodermal activity, heart rate, and ratings of mood and physical symptoms were recorded continuously or at specified intervals. Catecholamine excretion rates, autonomic reactions, reaction times, and ratings of subjective alertness showed changes typical for night-shift work. No main effects of noise were found, but significant interactions between the two experimental factors reflected differential actions of noise dependent on the type of shift. The results favor a multiple-arousal concept. Night-shift work primarily influences general arousal, while noise affects both general and goal-directed arousal, dependent on the presentation during day or night shift.

Combined effects of shiftwork and environmental hazards (heat, noise, toxic agents).

The paper deals with the results of studies or discussions concerning the problem of nightwork combined with other adverse working conditions. Special emphasis is laid on the untoward effect of high temperature during nightwork, as well as on noise and exposure to chemicals. It is shown that there is no substantial influence of heat stress on the circadian rhythm of adrenaline excretion under sitting working conditions with the subject performing a difficult mental task at warm climates up to 30 degrees C BET. Shiftwork and noise induce independent different effects which can be explained in terms of activation for shiftwork and in terms of tension for noise. The combination of both adverse exposures is therefore partly subtractive but partly additive as night work and noise negatively affect daysleep. Practical experience in the field of combined effects of shiftwork and chemical agents is lacking, but theoretical speculations lead to the conclusion that there may exist a time of day dependence of some chemicals, used at workplaces.

Subjective health status of day and shift-working policemen.

To assess the subjective health status of day- and shift-working police officers, a questionnaire-based study was carried out. All the day-workers had previous shift experience. To control the age factor the total population of 2659 shift-working and 1303 day-working police officers was divided into four ten-year age classes. Factor analysis revealed that all the symptoms included in the questionnaire could be grouped into six factors. The prevalence rates of complaints showed that four of these factors (autonomous symptoms, musculo-skeletal symptoms, disturbance of appetite and indigestion, respiratory infections) were influenced by the main effects of age and shift work. Across all age classes the age-related changes in prevalence rates were strengthened by shift-work. In the other two factors (nervous symptoms, gastro-intestinal symptoms) an additional interaction effect could be observed. While the prevalence rates of the day-workers increased with age, those of the shift-workers decreased in the oldest age class. This drop of prevalence rates may be attributed to the influence of selection processes.

Comparison of two analytical procedures for the determination of free urinary catecholamines under the demands of shiftwork experiments.

A typical shiftwork experiment was chosen to prove the validity of an automated procedure for the analysis of free noradrenaline and adrenaline in urine. The method consists of a column switching technique with an adsorption/elution clean-up and a reversed phase high performance liquid chromatography followed by chemical reaction detection based on the trihydroxyindole method. The analysis of variance was performed using a second data set obtained by a semi-automated procedure for which the accuracy had already been confirmed. The analysis of covariance showed that for field studies, as well as for laboratory experiments in which the variances contributed by the experiments themselves are greater than 10% rel., the data sets of the two methods provide the same information.

Circulatory and respiratory responses to muscular exercise in Czech and Norwegian children.

This paper presents a comparison between Czech and Norwegian rural healthy children with regard to the functional characteristics of the circulatory and respiratory system based upon work physiological variables and measurements of some pulmonary volumes. The study included randomised samples of boys and girls at the age of 8, 12 and 16 years, 66 Czech boys and 63 girls, 54 Norwegian boys and 57 girls. At the age of 8 years the maximal aerobic power was closely similar in both countries, but in the older age groups the Norwegian children exhibited lower physical fitness. The maximal heart rate was close to 200 min-1 on the average without any sex, age or ethnic differences. In agreement with the higher maximal aerobic power the 12 and 16 year old Czech children had lower submaximal heart rates for the same oxygen uptake than the Norwegian children. The forced vital capacity and forced expiratory volume in one second was significantly higher on the average in Czech than in Norwegian children but the latter, expressed in percent age of the former, averaged 87 to 91% without any sex, age or ethnic differences. The maximal ventilation volumes during muscular exercise reached higher values in Czech than in Norwegian children of the same age, but the mean maximal respiratory rate was close to 60 min-1, being independent of age, sex and cultural differences. During heavy exercise only 40 to 50% of the vital capacity and 45 to 55% of the forced expiratory volume were taken into account and this index of pulmonary function did not differ with sex, age or ethnic differences.

Working ability and exercise tolerance during treatment of a mild hypertension. I. Comparison between a beta-adreno-receptor blocking drug and a calcium antagonist.

A randomized cross-over trial was undertaken on 21 occupationally active persons who had a stable mild or moderate hypertension with the purpose of comparing the effect of a beta-adreno-receptor blocking agent (atenolol) with that of a calcium channel inhibitor (nifedipine). The doses recommended by the manufactures were used. Atenolol (100 mg) given once a day resulted in a marked hypotensive effect at rest as well as during exercise, the compliance was satisfactory, and the hemodynamic changes were not reflected in unfavourable side effects during muscular exercise or in the subjects own personal assessment of fatigue during the exercise tests which ranged in energy expenditure from about three to six times the resting level. However, unfavourable, modest side effects occurred in two subjects during atenolol medication to the extent that they wanted to terminate the study. Nifedipine therapy with doses of 10 mg, three times a day, resulted in a modest, but statistically insignificant reduction in arterial blood pressure, which contrasts with previous published results. It is suggested that the modest effect is caused or related to the poor compliance and a daily dose that was quantitatively too small. No unfavourable side effects were seen during muscular efforts when the subjects were on nifedipine medication.

Working ability and exercise tolerance during treatment of mild hypertension. II. A comparison between atenolol and prazosin medication.

The treatments of mild hypertension with atenolol and prazosin in occupationally active men and women were compared in a double blind cross-over with placebo. The hypotensive effect of the beta-adreno-receptor blocking drug, atenolol, were striking and in accordance with current knowledge, using one daily dose of 100 mg. In contrast, the hypotensive effect of taking 2 mg prazosin twice a day was modest, averaging about 3% when compared with placebo, somewhat less but still detectable during the performance of muscular exercises. Atenolol medication significantly reduced heart rate and blood pressure responses to muscular exercises, covering a range of work loads experienced during ordinary working days. No increased feeling of muscular fatigue or other discomfort during muscular work compared to that on prazosin and placebo medication could be detected. It was therefore concluded that atenolol medication was a useful treatment of mild hypertension and did not reduce the normal working ability and exercise tolerance. Prazosin medication did not significantly change working ability and exercise tolerance.

Leisure time sport activities and maximal aerobic power during late adolescence.

The pattern of leisure time sport activity was estimated by retrospective recalls and expressed in terms of an annual sport activity score. The activity score was related to the development of maximal aerobic power during the period of late adolescence in German children. Both girls and boys reduced their activity pattern from 14 to 18 years of age, boys more than girls. At each age boys were more active than girls. A slight tendency towards better fitness with increased habitual physical activity was noticed, but many sedentary children exhibited a good performance capacity and some children with a high level of leisure time sport activity were characterized by a low level of maximal aerobic power. A statistical analysis revealed that the observed tendency to better fitness with increased habitual physical activity could be explained by an age factor with no additional effect of variation in sport activity score.

Analysis of 120 shift systems of the police in the Federal Republic of Germany.

120 shift rotas of the police were collected and analysed. The frequency distribution of the shift cycles, the duration of shifts, the start and end of shifts, the maximal number of consecutive night shifts, as well as the frequency of different kinds of free weekends, were determined. The shift systems are compared with recommendations for the design of shift rotas which are based on physiological, psychological and social criteria.