Effects of time of day and the wingate test on appetite perceptions, food intake and plasma levels of adipokines

It has been demonstrated that several aspects of adipose-related physiology including adipokine release, exhibit daily oscillations. Physical exercise exerts a strong influence on adipokine release and a possible reverse disruption of peripheral circadian clocks. The aim of this study was to establish the effects of time of day and the Wingate test on appetite perception, food intake and plasma levels of adipokines. Twenty-four moderately active non-smoking males (mean ± S.D. age: 27.1 ± 3.1 years; height: 1.79 ± 0.1 m; weight: 76.1 ± 11.7 kg) were recruited for this study and divided in two groups; one fed with an ad libitum test meal and another one without an ad libitum test meal. Each subject participated in the following studies performed at 11:00 and 23:00 hours on separate days: 1) Exercise study (ES): a 30-second Wingate Anaerobic Test (WAnT), and 2) sedentary study (SS). Subjects rated their appetite perceptions (hunger and prospective food consumption) on a 100-milimeter visual analogue scale (VAS) at baseline, after exercise, after test meal and during the postprandial/control period. At those time points blood samples were obtained for the measurement of plasma leptin, visfatin and apelin concentrations. Appetite perception and energy intake results at test meal decreased in response to WAnT in comparison with sedentary subjects. Time of day had no statistically significant effect on energy intake but the appetite perception score after test meal at 24:00 hours was statistically higher than that after test meal at 12:00 hours. No significant differences in the tested plasma adipokine concentrations between the trials existed at baseline, however, all plasma adipokine levels at 24:00 hours were higher than those at 12:00 hours. Plasma apelin concentrations after WAnT were significantly higher than its pre-exercise value at 12:00 hours, unlike those at 24:00 hours. Sedentary experiments showed a modest, yet significant, rise in plasma apelin levels after the test meal at 12:00 hours but not after the one at 24:00 hours. There were no significant changes in plasma leptin concentrations after exercise or test meal but a significant decrease in plasma visfatin concentrations after exercise intervention both at the 12:00 hours test and the 24:00 hours test has been observed. Test meals caused a significant rise in visfatin concentrations in sedentary, but not exercise series, in the daytime and nighttime tests. We conclude that time of day is an important aspect to consider in the relationships between exercise, metabolism and appetite. Further studies are needed to explain the specific mechanisms underlying the effects of acute exercise on postprandial physiology at different times of the day.

Nurses' health, age and the wish to leave the profession--findings from the European NEXT-Study

BACKGROUND AND OBJECTIVES

In many industrialised countries the number of workers with low health is expected to increase in the nursing profession. This will have implications for occupational health work in health care. The European NEXT-Study (www. next-study. net, funded by EU) investigates working conditions of nurses in ten European countries and provides the opportunity to evaluate the role of health with respect to age and the consideration of leaving nursing.

METHODS

26,263 female registered nurses from Belgium, Germany, Finland, France, England, Italy, Netherlands, Poland and Slovakia were eligible for analysis.

RESULTS

In most countries, older nurses considered leaving the profession more frequently than younger nurses. 'Health' was--next to 'professional opportunities' and 'work organisational factors'--strongly associated with the consideration of leaving nursing. However, more than half of all nurses with low health wanted to remain in the profession. This group reported rather positive psychosocial working conditions--but also the highest fear for unemployment.

CONCLUSIONS

The findings indicate that 'the nurse with low health' is reality in many health care settings. Both positive supporting working conditions but also lack of occupational alternatives and fear of unemployment may contribute to this. Current economic, political and demographic trends implicate that the number of active nurses with low health will increase. Occupational health surveillance will be challenged by this. But NEXT findings implicate that prevention also will have to regard work organisational factors if the aim is to sustain nurses' health and to enable nurses to remain healthy in their profession until retirement age.

Internal and external factors influencing time-related injury risk in continuous shift work

Time-related accident risk in shift work may be attributed to internal factors, such as fatigue, level of performance, sleep propensity, and to some external factors, like shift system, physical and social environment. Six hundred and sixty-eight events in the metallurgical industry have been analysed in terms of time of day, time on task, consecutive day of the shift block, day of the week, and season. The injury rate was similar on all shifts but more severe accidents happened in the nighttime. Somewhat more injuries occurred in the second half of the shift, in the second part of a shift block, and in summer compared with winter. There were fewer injuries at weekends.

The effects of nightwork on psychological changes during the menstrual cycle

This study investigated whether the temporal stress of working at night interferes with nurses' experience of different phases of the menstrual cycle. Twenty-four, rotating-shift nurses recorded data on a hand-held computer at the start and end of each day and every 2 hours during their shifts for a period of 28 days. The measures included a sleep diary, self-ratings of mood and symptoms, and two cognitive performance tasks. Using a pooled time series analysis, it was found that some of the self-report measures showed a significant interaction between type of shift worked and menstrual cycle phase. For example, alertness was found to be lower towards the end of the night shift during the premenstrual phase compared to other phase and shift combinations. However, some of the measures showed only main effects of cycle phase or were non-significant. Retrospective measures from a larger sample showed an association between the number of nights worked per year and duration of premenstrual and menstrual problems, and severity of premenstrual problems. The results suggest that nightwork may alter some aspects of nurses' psychological experience of the menstrual cycle.

Gender, ageing, and shiftwork intolerance

The study investigated the hypothetical differences between male and female shiftworkers in their susceptibility to shiftwork-related health and social problems, with the special reference to the role of the age factor. The comparison concerned two matched-for-age-and-occupation groups of men and women, each of 83 persons, selected from the larger studied population of more than 700 workers in a Polish steel plant. The subjects were crane-operators employed in the same forward-rotated, three-shift, four-team shift system, 4:4:4 with shift changes at 06:00, 14:00, 22:00; and 48 h off following each shift block. The investigation comprised a battery of questionnaires on demographic characteristics, sleep quantity and quality, subjective health complaints, and opinions on shiftwork. The analysis of data revealed that men slept more than women, especially when working on the afternoon and night shifts. The differences became more striking and significant for all work shifts and days-off when related to declared individual sleep requirements. Women experienced more sleep disturbances than men and suffered more frequently from drowsiness during work, especially when working the morning shift. The ratings of subjective health were lower in women, with exception of respiratory complaints. Women generally suffered more than men from symptoms considered as specific to the 'intolerance syndrome', i.e. psychoneurotic, digestive, circulatory, and those of chronic fatigue. However, after passing the 'critical decade' of 40-50 years their subjective health generally improved, whereas in males one observed the consequent deterioration of health with advancing age. Women more often complained about their health and went to see the doctor, but on the other hand, they did not tend to quit shiftwork as often as did their male counterparts.