[Experimental research in the rat using chronobiologic methods simulating various work shifts of man]

Certain diseases associated rightly or wrongly with the exposure to excessive burdens, physical or emotional, have been claimed to be more frequent among shiftworkers, notably when work involved conditions with different interacting loads. As an example, one could focus upon apparent contradictions in the literature concerning shiftwork and ulcers: Doll and Jones report on a total of 4871 workers, either shiftworkers or not, that the incidence of ulcers was slightly lower, rather than higher, in shiftworkers. By contrast Duesberg and Weiss, comparing shiftworkers and employees working in a regular work day, found higher incidence of ulcers in shiftworkers. Bonnevie compared night-workers and day-workers and found that the ulcer incidence for the first type was 15% and for the second 5%. Moreover he points out that some individuals cannot cope with the shiftwork and show signs of gastric ulcer more often. Ulcerogenesis was investigated on a sperimental model (rats), following chronobiological methods. It was found that there is a statistically significant difference on the gastric sensibility between rats treated with multiple loads at first morning hours or evening; there is a large sensibility during morning hours that is during the rest period of rats.