RESUMO
It is well known that shift work produces fatigue. This effect is enhanced in seniors and could be potentiated by physical and psychosocial job demands. The aim of this study was to investigate the combined effects of work-related risk factors, age and shift work on fatigue. The field study was performed based on a questionnaire about sleep characteristics, environmental work-place exposure and fatigue level. Objective noise exposure was also measured. The samples were composed of 201 shift workers of a chemical industry in France. They were divided into two age groups [<40 and >40 years]. No significant effect of temperature, vibration, chemical agents, ergonomics and psychosocial factors was found on fatigue. However, noise exposure resulted in an increase in subjective fatigue [P<0.0001]. Older shift workers reported more fatigue than the younger ones [P<0.01]. Concerning sleep characteristics, sleep duration progressively decreased from evening to morning shifts, night shill being intermediate [P<0.01]. Older shift workers reported more sleep fragmentation [P<0.01], longer sleep duration in the morning shifts [P<0.05] and lesser in the night shifts [P<0.001]. Combined effects of noise exposure and age were observed on sleep quality of night workers [P<0.01]. Older workers are less able to adjust to night work especially if they work in the noisy environments