Effects of diurnal and seasonal sleep deficiency on work effort and fatigue of shift workers.

This study was designed to assess and compare the quantity and quality of sleep of morning, afternoon, and night shift workers during the winter and summer seasons, and to evaluate the effects of sleep deficiency on the work effort and fatigue of the workers. The subjects studied consisted of a sample of 150 textile workers, working on a monthly rotating 3-shift system: morning shift (06.00-11.00 and 14.00-17.00) afternoon shift (11.00-14.00 and 17.00-22.00), and night shift (22.00-06.00). Information concerning quantity and quality of sleep were registered daily over a week for every subject. The Ratings of Perceived Effort scale and the Feeling and Symptoms of Fatigue scale were used to collect information about feeling of effort and fatigue of the subjects. The results showed that the duration of sleep length is longest in the afternoon and shortest in the night shift both during summer and winter. The amount of sleep is shorter during summer during all three shifts. The workers spent more effort and felt more fatigued during summer than winter. The shift workers, particularly of the tropical region, like Bangladesh, seem to be worst affected in terms of quantity and quality of sleep, health and well-being due to extremely high temperature (30-45 degrees Celsius) during summer than winter (5-25 degrees Celsius). The workers think that the problems of shift work could be minimized by improving the quality of working and living conditions, reducing cycle of rotation, shortening working day and closing night shift during peak summer.