Circadian rhythms in plasma concentration of 11-hydroxycorticosteroids in men working on night shift and in permanent night workers

Conroy, R. T. W. L., Elliott, Ann L., and Mills, J. N. (1970).Brit. J. industr. Med.,27, 170-174. Circadian rhythms in plasma concentration of 11-hydroxycorticosteroids in men working on night shift and in permanent night workers. Blood samples have been collected for estimation of plasma 11-hydroxycorticosteroids from three groups of workers - day and night shift workers in a light engineering factory, and night workers in a newspaper printing works. Up to five samples were collected over 24 hr, or two samples per 24 hr were collected for three days. In conformity with the observations of others, day workers showed maximal concentrations in the morning around the time when they started work. In the newspaper workers maximal concentrations were found when they awoke around 14·00 hr. Night shift workers in the engineering works showed a greater variety of pattern, some showing the pattern usual in a day worker, some showing a maximum concentration about midnight and a minimum around 06·00 hr and a large proportion showing no clear circadian rhythm.

In the newspaper workers the rhythm was thus well adapted to their pattern of nocturnal work, whereas relatively few of the night shift workers in the engineering works showed such adaptation. It appears that the adrenal cortical rhythm can be adapted to night work in a community in which this is universal, accepted and lifelong, but that such adjustment is unusual in men on night shift work for limited periods, and whose associates are mainly following a usual nycthemeral existence.

     

Circadian rhythms of seven heavy metals in plasma, erythrocytes and urine in men: observation in metal workers

To elucidate circadian rhythms (variation within a day) of 7 toxic or essential metals in plasma and erythrocytes in relation to the rhythms in urine in men, 19 male metal foundry workers were examined; they were exposed to lead (Pb), zinc (Zn) and copper (Cu) occupationally but separated from the exposure during the study. Circadian rhythms were found for plasma concentration of Pb, cadmium (Cd), Zn, Cu and chromium (Cr) in the workers. Circadian rhythms were also found for Pb, inorganic mercury (Hg), Zn and Cr in erythrocytes and for all metals except Zn in urine. Both the plasma and urinary levels of Pb, Cd, Cu and Cr together with urinary excretion of Mn and creatinine tended to decrease during night hours; both the erythrocyte and urinary levels of Hg together with both the plasma and erythrocyte levels of Zn tended to increase during morning hours. The results of profile analysis suggested that the circadian rhythm of Pb in urine was affected more strongly by its plasma and erythrocyte rhythms than by the rhythm of creatinine in urine, i.e. the rhythm of glomerular filtration; the urinary rhythms of Cd, Cr, and Mn were affected more by the creatinine rhythm; and the urinary rhythm of Cu was affected by both its plasma and creatinine rhythms. On the other hand, the urinary rhythm of Hg was assumed to be independent of the creatinine rhythm and be affected by its erythrocyte rhythm. The present study suggested that different biological limit values might be needed for different hours of the day especially for shift workers who are exposed to various heavy metals. Instead, further studies should be conducted to find the adjustment methods by which no circadian rhythms are discerned.     

Circadian rhythms in the urinary excretion of metals and organic substances in "healthy" men

Circadian rhythms in the urinary excretion of metals and organic substances were examined in ten "healthy" men under conditions of water loading and restriction. Four characteristic rhythms were observed: (1) decreased excretion during the night for lead and urinary flow rate; (2) decreased excretion of hippuric acid, delta-aminolevulinic acid, coproporphyrin, creatinine, and total urinary solutes during the night and morning hours; (3) increased excretion of mercury and zinc during the morning hours; and (4) no significant variation for copper. Excretion of lead, hippuric acid, delta-aminolevulinic acid, and total urinary solutes was significantly correlated with urinary flow rate and creatinine excretion, which suggested that their circadian rhythms were the consequence of reduced glomerular filtration and increased reabsorption by the distal tubule and collecting duct during the night and morning hours. Similarly, it was suggested that the mercury and zinc rhythms resulted partly from increased reabsorption during the night hours; the coproporphyrin rhythm reflected reduced glomerular filtration of coproporphyrinogen during the night and morning hours.     

Sleep and wakefulness in a group of shift workers

Tune, G. S. (1969).Brit. J. industr. Med.,26, 54-58. Sleep and wakefulness in a group of shift workers. Fifty-two shift workers recorded their hours of sleep and wakefulness for a period of 10 weeks. Compared with matched non-shift-working control subjects it was found that they took a higher average duration of sleep per 24 hours and more and longer naps outside the major sleep period. A comparison of the on and off duty records from the shift workers showed that a sleep debt was incurred during the former which was largely paid off by taking long naps in the latter. It is suggested that the longer sleep taken by shift workers may be necessary in order to pay off specific kinds of sleep debt.     

Circadian rhythms in the urinary excretion of heavy metals and organic substances in metal workers in relation to renal excretory mechanism: profile analysis

Summary Circadian rhythms in the urinary excretion of eleven heavy metals and organic substances were examined under free, water-restrictive and water-loading conditions for 6 d (2 d for each of the three conditions) in twenty metal workers exposed to lead, zinc and copper. Circadian rhythms were found for all heavy metals and organic substances as well as for urinary flow (UF) rate, creatinine (Cn) and total urinary solutes (TUS). The Cn rhythm was significantly unparallel to the OF rhythm under the water-loading condition, indicating that the two rhythms were essentially different from each other. Circadian rhythms of the eleven urinary substances were then related to the Cn and OF rhythms, using profile analysis. The results indicated that the rhythms in the manganese, chromium, copper and beta-2-microglobulin excretion depend on the Cn rhythm, i.e. the rhythm of glomerular filtration; the rhythms in the hippuric acid, delta-aminolevulinic acid and TUS excretion are on the OF rhythm, i.e. the rhythm of reabsorption by the distal tubule and collecting duct. On the other hand, the rhythms in the lead, inorganic mercury, cadmium, zinc and coproporphyrin excretion were considered as reflecting complex renal excretory mechanisms.     

Circadian rhythms of body temperature in shift-workers at a coalface

Colquhoun, W. P., and Edwards, R. S. (1970).Brit. J. industr. Med.,27, 266-272. Circadian rhythms of body temperature in shift-workers at a coalface. The oral temperatures of a group of coalface workers were recorded daily at intervals during their period of work underground, over a three-week cycle of day, afternoon and night shifts. The basic mean circadian rhythm of temperature observed in the group as a whole was similar in phase and in amplitude to that of a control group of young men unused to shift work. However, it appeared that the rhythm of older coalface workers differed to some extent from that of their younger colleagues, since the mean temperature in the second half of the night was significantly higher in the older men. Whether this difference is permanent, and whether it is due to age alone rather than to long experience of night-shift working, has yet to be determined.

There were indications that the changes in the mean on-shift trend in temperature during the week in response to successive days of an altered sleep-waking routine were more pronounced, in the group as a whole, than the changes observed in a control group of young men when the latter were exposed to similar unusual routines.

It is recommended that these findings be substantiated on a considerably larger number of coalface workers before their implications for shift working are considered.

     

The impact of a week of simulated night work on sleep, circadian phase, and performance

Methods: Fifteen healthy subjects participated in an adaptation and baseline night sleep, directly followed by seven simulated eight-hour night shifts (2300 to 0700 hours). At the end of each shift they were taken outside and exposed to natural light for 20 minutes. They then slept from approximately 0800 hours until they naturally awoke.

Results: There was a significant increase in mean performance on a visual psychomotor vigilance task across the week. Daytime sleep quality and quantity were not negatively affected. Total sleep time (TST) for each of the daytime sleeps was reduced, resulting in an average cumulative sleep debt of 3.53 hours prior to the final night shift. TST for each of the daytime sleep periods did not significantly differ from the baseline night, nor did TST significantly vary across the week. There was a significant decrease in wake time after sleep onset and sleep onset latency across the week; sleep efficiency showed a trend towards greater efficiency across the consecutive daytime sleeps. Hours of wakefulness prior to each simulated night shift significantly varied across the week. The melatonin profile significantly shifted across the week.

Conclusions: Results suggest that under optimal conditions, the sleep debt that accumulates during consecutive night shifts is relatively small and does not exacerbate decrements in night-time performance resulting from other factors. When sleep loss is minimised, adaptation of performance during consecutive night shifts can occur in conjunction with circadian adaptation.

     

Apparent phase-shifts of circadian rhythms (masking effects) during rapid shift rotation

Summary Six subjects worked an experimental 8 h rapidly rotating shift system in which 6 shifts were compressed into 5 d (work two mornings—8 h interval—work two nights—8 h interval—work two afternoons). Rectal temperature was continuously recorded and urinary excretion rates of adrenaline, noradrenaline, K⁺, Na⁺ and Hg` were assessed in samples collected at 4 h intervals. Higher rectal temperatures and higher excretion rates of the two catecholamines than those expected from the normal circadian rhythms were observed during night work, while lower than expected values were recorded during forenoon sleep. In these three rhythms, immediate, significant 3-4h delay phase-shifts occurred in the two days following night shifts. The acrophases reverted suddenly to their initial positions when the subjects returned to their normal sleep/wake schedule. The circadian rhythms of the excretion of electrolytes were not perceptibly disturbed. It is concluded that the apparent phase-shifts were due to a direct influence (masking effect) of the changes in body functions during sleep and wakefulness on the measured parameters, and that no true phase-shifts (entrainment) occurred in the endogenous circadian regulation. The evidence of such an immediate, partial adaptation to unconventional sleep/wake patterns supports the adoption of rapidly rotating shift systems which would not greatly interfere with the endogenous oscillators.     

Absence from work in relation to length and distribution of shift hours

Walker, J., and de la Mare, Gwynneth (1971). Brit. J. industr. Med., 28, 36-44. Absence from work in relation to length and distribution of shift hours. A long period on night shift or even permanent night work has sometimes been suggested for those on continuous shift work to allow circadian rhythms to adapt. As the weekly hours of work have been reduced there is some evidence that a permanent night shift is practical, and about 12% of all shift workers are on this type of work. However, the case for permanent night shift must be established on grounds of both effectiveness and acceptability.

The present study compares the absence experience, including sickness absence, of permanent day workers and permanent night workers matched for age and job in three undertakings which contained a range of working conditions.

The question of the relationship between absence from work and total hours worked including overtime has been reopened, and in comparing absence from work according to the type of shift the total hours worked must also be taken into account. The relationship between the average hours when a man was at work and the amount of absence was tested. The men in the three undertakings worked a wide range of voluntary overtime.

The results showed that in two undertakings long-term absence, mainly sickness absence, was higher on the night shift than on the day shift; and, in the third, absence was about the same on the two shifts. As the work load was less in the two undertakings with a higher absence on the night shift it was suggested that selective factors were operating. These results may be contrasted to studies which have compared the absence of rotating shift workers and day workers.

In all three undertakings there was a tendency for absence to be less among high overtime workers than among those who worked medium or small amounts of overtime, although the trends were not consistent. There was no evidence at all that high overtime and absence from work were positively associated.

The implications of these results are discussed.

     

Attention and working memory in resident anaesthetists after night duty: group and individual effects

Aims: To investigate the effects of a single period of night duty on measures of attention and working memory in a group of residents (registrars) in anaesthesiology. Emphasis was placed on individual deficits using a reference point of the equivalent effect of a blood alcohol concentration (BAC) >0.05% determined by other researchers.

Methods: There were 33 subjects aged 26–42 years. Night duty was performed on a weekly basis. Baseline assessments were conducted at either 08 15 or 08 55 preceding night duty and repeated 24–25 hours later, just after the completion of duty. Questionnaires included items regarding duration of sleep and the Stanford Sleepiness Scale. A battery of four reaction time (RT) tasks of increasing difficulty, lasting approximately 35 minutes, was administered on a personal computer. These ranged from simple RT to progressively more complex RT tasks incorporating working memory. A significant change was regarded as >15% deterioration in respect of speed or accuracy.

Results: The mean duration of sleep preceding night duty was 7.04 hours and 1.66 hours during the period of night duty. Intergroup comparisons revealed significant prolongation in mean response speed in the first three tests. Mean accuracy was significantly reduced only in respect of the two more complex tests. A >15% deterioration in response speed occurred in up to 30% of subjects on a single task, rising to 52% (17/33) overall. Deterioration occurred in a patchy distribution in most subjects, involving no more than one or two of the four tasks. As regards accuracy, the prevalence of deterioration increased with task complexity.

Conclusions: Results are in general agreement with previous group analyses. A new dimension was added by the analysis of a broad spectrum of individual response to sleep deprivation. The effects of sleep loss in residents cannot be overlooked, even in a relatively benign work schedule.

     

化学性肝损害与肾上腺皮质激素 Ⅲ.趋肝毒物四氯化碳、氯乙烯对作业工人肾上腺皮质功能的影响及其与肝损害的关系

本文对生产和使用CCl_4和氯乙烯的工人进行了肝功能和肾上腺皮质功能检测。结果表明,工人长期在较高浓度的CCl_4和氯乙烯车间劳动,接触CCl_4工人的血浆皮质醇水平降低占25.9%,氯乙烯工人血浆皮质醇水平升高占21.7%,但未发现皮质激素水平改变与肝损害间有明显关系。     

Chronic exposure to zinc of furnace operators in a brass foundry

Hamdi, A. E. (1969).Brit. J. industr. Med.,26, 126-134. Chronic exposure to zinc of furnace operators in a brass foundry. Twelve furnace operators with chronic exposure to zinc oxide fumes in a brass foundry and 10 normal non-exposed control subjects were studied. Simultaneous determinations of zinc concentrations in the plasma, blood corpuscles, whole blood, and urine were made for each worker and control subject, and in the basal fasting gastric juice and in the gastric secretion half an hour and one hour after gastric stimulation by alcohol in eight workers and seven control subjects.

The workers showed a statistically significant increase of zinc concentration in the blood corpuscles, whole blood, and basal fasting gastric juice compared with the control subjects. Urinary zinc excretion was slightly increased in the exposed workers. The increase in the plasma zinc in the workers was not statistically significant.

Stomach aspiration after alcohol showed a depression of the mean zinc concentration in the gastric secretion after half an hour with a subsequent increase to approximately the fasting level after one hour in both the normal subjects and the workers. Mean zinc concentrations in the gastric juice half an hour and one hour after stomach stimulation were higher in the workers, but the increase was not statistically significant.

It is suggested that the zinc absorbed by these workers is rapidly eliminated from the plasma to be excreted through the gastro-intestinal and urinary tracts; excess zinc is stored in the blood corpuscles. The increased zinc concentration in the gastric secretion of these workers might account, in part, for the high incidence of gastric complaints among them.

     

Changes in the excretion of corticosteroids and catecholamines in tractor-drivers

Summary An investigation was carried out to study the effect of mechanized agricultural work on the excretion of some corticosteroids and catecholamines in tractor-drivers during a seasonal field work. Group 1 (15 subjects) was examined three times: in the morning hours before starting work and at two intervals during the first and second half of the working day. In group two (11 subjects) the characteristics of the circadian rhythm for 24 h were investigated in urine collected at six intervals.The results from both studies disclose a considerable increase of the total 17-ketosteroids, total 17-oxycorticosteroids, free 11-oxycortico steroids, noradrenaline and adrenaline excretion levels which indicates overactivity of the hypothalamic-pituitary-adrenal and sympathetic nervous systems. The circadian rhythms of the examined parameters are characterized by an increasing of the mesors and a lowering of the amplitudes of the rhythmic variations. No significant changes of corticosteroids and catecholamines are established. Considerable interindividual differences in the course of excretion of the studied indices as well as the lack of marked circadian rhythm in about 50% of the subjects are found.     

Measurement of urinary mercury excretion by atomic absorption in health and disease

Taylor, A., and Marks, V. (1973).British Journal of Industrial Medicine,30, 293-296. Measurement of urinary excretion by atomic absorption in health and disease. Excretion of mercury was measured by a cold-vapour atomic absorption technique on samples of urine from five groups of people having varying exposure to mercury.

Serial investigations of up to 14 days were carried out on eight subjects to determine the temporal relationship between exposure and excretion.

Subjects with no exposure excreted 0-10 μg mercury per gramme creatinine. Similar values were found in laboratory staff and men assembling hollow cathode lamps. Excretion of mercury by dental workers was significantly increased. No correlation between exposure and excretion of mercury was seen in the subjects investigated.

The significance of measuring urinary excretion in the detection of mercury intoxication is discussed. The suggestion is made that urinary mercury excretion of more than 20 μg/g creatinine or 40 μg mercury per 24 hours should be considered evidence of recent or remote exposure to mercury. It is concluded that measurement of urinary mercury excretion is important in revealing those persons who may ultimately develop symptoms of toxicity.

     

Use of Single Urine Samples for the Assessment of Lead Absorption

The variation of urinary lead concentration (μg. Pb/litre) of short-period samples has been studied in a group of men exposed to inorganic lead dust. The urinary specific gravity was used to correct for the variation in urinary volume, but the residual variation was still too great to assess the mean lead concentration. The effect of creatinine correction was studied as an alternative, but there is no statistical difference between either method of correction. It is shown that the variation of lead concentration is related to the time of day. The highest concentration occurs at approximately 4.00 p.m. in day workers.

The diurnal rhythm of the lead excretion rate (μg. Pb/minute) is described in day and night shift workers. The rate of excretion rises to a maximum at approximately 5.00 p.m. in the former but decreases in night workers, falling to a minimum at approximately 2.00 a.m. The rhythm is independent of immediate exposure and is thought to be physiological in origin. The plasma lead clearance is estimated at 1·4 ml. plasma per minute. This suggests that only a small proportion of plasma lead may be ultrafiltrable and that little lead is secreted by the tubules.

     

Melatonin, sleep, and shift work adaptation

BACKGROUND: Night work is associated with disrupted circadian rhythms, fatigue, accidents, and chronic disease. Melatonin secretion helps regulate sleep and circadian rhythms. OBJECTIVE: Melatonin, sleep disturbances, and symptoms (sleep, fatigue, mental) were compared among workers on permanent day, swing, and night shifts. METHODS: Urinary 6-hydroxymelatonin sulfate (6-OHMS) was measured in postwork and postsleep samples. Disrupted circadian melatonin production was evaluated using the sleep:work 6-OHMS ratio. Wrist actigraphy characterized light exposures and sleep characteristics. RESULTS: Night workers had altered melatonin, disrupted sleep, and elevated symptom prevalence. Subjects grouped by their sleep:work 6-OHMS ratio rather than shift had even greater symptom prevalence. Risks for two or more symptoms were 3.5 to 8 times greater among workers with sleep:work ratios < or =1 compared to those with ratios >1. CONCLUSIONS: This ratio may help identify workers at increased risk for accidents or injuries.     

Calciuric Effects of Short-Term Dietary Loading of Protein,Sodium Chloride and Potassium Citrate in Prepubescent Girls

Objective: Studies using adult human subjects indicate that dietary protein and sodium chloride have negative effects on the retention of calcium by increasing urinary calcium excretion, while alkaline potassium improves calcium retention along with decreasing urinary calcium losses. This study investigated the effect of these dietary factors on acute urinary calcium excretion in 14 prepubescent girls age 6.7 to 10.0 years.

Methods: Subjects provided a fasting urine sample then consumed a meal containing one of five treatments: moderate protein (MP) providing 11.8 g protein, moderate protein plus 26 mmol sodium chloride (MP+Na), high protein (HP) providing 28.8 g protein, high protein plus 26 mmol sodium chloride (HP+Na), or high protein plus 32 mmol potassium as tripotassium citrate (HP+K). Urine was collected at 1.5 and 3.0 hours after the meal. Supplemental protein was given as 80:20 casein:lactalbumin. Test meals were isocaloric, and unless intentionally altered, components of interest except phosphate were equal between treatments. Each subject completed all five treatments.

Results: Urinary calcium excretion rose after the meal, peaking at 1.5 hours. There were no significant differences in calcium excretion between treatments at any time point. The high protein treatments did not result in a significant increase in either net acid or sulfate excretion at 1.5 hours compared to moderate protein. Dietary sodium chloride had no effect on urinary sodium or calcium excretion over the 3 hours. After the potassium treatment, sodium excretion increased (p≤0.002) and net acid excretion decreased (p<0.001) compared to other treatments at 1.5 hours.

Conclusions: In children, a simultaneous increase in protein and phosphorus due to increased milk protein intake did not increase acute urinary calcium excretion. An effect of dietary sodium chloride on acute urinary calcium excretion was not observed. Both these findings were similar to those of adult studies previously conducted in the same laboratory using similar format and treatments. Potassium citrate was not hypocalciuric in children, a response differing from that for adults, who have shown a decrease in acute urinary calcium excretion in response to alkaline potassium treatment. Further characterization of calciuric responses to dietary factors is required for children, who may differ from adults in many respects.     

Nutritional and environmental studies on an ocean-going oil tanker. 2. Heat acclimatization and nutrient balances

Collins, K. J., Eddy, T. P., Hibbs, A., Stock, A. L., and Wheeler, E. F. (1971).Brit. J. industr. Med.,28, 246-258. Nutritional and environmental studies on an ocean-going oil tanker. 2. Heat acclimatization and nutrient balances. On the oil tanker S.S. Esso Newcastle, metabolic balances were investigated in three medical students and three working members of the crew during three-day experiments conducted when the ship was located in Biscay, the South Atlantic, and the Persian Gulf. Information was sought on the possible changes in nutrient requirements and the significance of the losses of nutrients in sweat when the subjects became acclimatized to heat. Physiological parameters of acclimatization were measured on each subject by controlled hyperthermia using a heated test-bed. Details are also given of the procedures devised for measuring the daily intake and loss of nutrients in metabolic balance studies on working subjects.

The intakes of water, sodium (including salt supplements), potassium, nitrogen, and iron provided by the ship's diet were found to be adequate, or more than adequate, during the outward voyage to the Persian Gulf. In two crew subjects who worked in the engine room, there was a trend to more positive salt and water balance with sweat losses of 3 to 4 litres per day in the Persian Gulf, but not in the three students who, though artificially acclimatized, were seldom exposed to hot working conditions. Sweat concentrations of sodium, potassium, and nitrogen were related to the rate of 24-hour sweat loss but were not altered by heat acclimatization. In the environmental and dietary conditions on board, the effect of daily sweat losses of potassium, nitrogen, and iron on the respective balances was found to be insignificant.

The urinary output of 17-OH corticosteroids increased slightly in mid-voyage in the students but was not raised in either students or crew in the Persian Gulf. There was evidence of temporary increases in plasma cortisol accompanied by negative nitrogen and potassium balances when unacclimatized crew members were exposed to heat stress at the start of the voyage.

     

Measurement of net acid excretion by use of paper strips

OBJECTIVE: Net endogenous acid production, reflected in the steady state as net acid excretion (NAE), is implicated in bone loss because it is positively associated with urinary calcium loss. Protein is one of the main sources of dietary acid load, whereas fruit and vegetables provide alkaline potassium salts that counteract the dietary acid load. This study investigated whether a pH paper strip measurement of overnight (i.e., first void) urine would reflect 24-h NAE, measured as excretion rates of titratable acid minus bicarbonate plus ammonium. METHODS: Twenty-three subjects collected 24-h urine in two parts: day (approximately 7 am to 11 pm) and overnight (approximately 11 pm to 7 am). At first void, subjects recorded pH using paper strips. Subjects recorded intake and 20 subjects provided fasting urine collected from 7 to 9 am. RESULTS: The pH paper strip measurements of first void urine was significantly correlated with 24-h titratable acid minus bicarbonate (r = -0.466, P < 0.025) but not with 24-h NAE. We examined the association of dietary protein, potassium, protein:potassium ratio, and sodium with NAE, with fasting morning urinary calcium excretion, an indirect measurement of bone loss, and with urinary cross-links, a direct measurement of bone resorption. Of these, only sodium intake (measured as 24-h urine excretion) and urine potassium:sodium ratio showed a significant relation (with fasting calcium excretion). CONCLUSIONS: We did not find that the first void urine pH by paper strip measurement provided an index of daily net endogenous acid production as reflected in 24-h NAE. In our sample of young adults, daily sodium intake positively correlated with bone resorption, as reflected in fasting urine calcium, whereas daily NAE did not.     

Studies on fatigue and shift work in nurses]

Effects of shift work on physiological parameters and autonomic nervous-adrenal system were studied on six hospital nurses. Their body temperature, heart rate, blood pressure, fluctuation in ECG R-R intervals, serum catecholamines and cortisol, and subjective fatigue ratings before and after day, evening and night shift were determined. Furthermore, mean heart rates, walk steps, estimated energy expenditure, and urinary catecholamine excretion were determined three times for eight hours each during each shift work day. The following results were obtained: 1) No significant changes were detected in the physiological parameters before and after each shift work, except for elevation in plasma adrenaline level after night shift. 2) Heart rate, blood pressure and subjective fatigue rating tended to be higher, though not significantly, at the beginning of night shift, when compared with the data obtained on the some time of day, i.e., at the end of evening shift. 3) On the other hand, the plasma cortisol level tended to be suppressed after night shift, suggesting that even one night shift work may change the circadian rhythm of plasma cortisol. 4) Statistical analyses showed that in contrast to day and evening shift, in night shift there was no significant positive correlation between eight-hour walk steps, and eight-hour mean heart rate and urinary adrenaline excretion, suggesting an altered circadian rhythm in heart rate and urinary adrenaline excretion and also a possible additional psychological load in night shift. These results suggest that even one night shift work could modulate the autonomic nervous-adrenal activity of hospital nurses, compared with day or evening shift, and indicate that it is necessary to lengthen the time interval before and after night shift work.