Many other employees are routinely working in the evenings or overnight, apparently without being classified as shift workers. These hours have a serious impact on workers and their families. Shift workers have little opportunity to interact in social or family gatherings, and are under enormous strain and stress in coping with everyday issues, both on and off the job. Studies compiled by the Circadian Learning Centre in the United States have shown that shift workers, especially those who work nights, can suffer from a number of health problems. They include sleep disorders, fatigue, heart disease, high blood pressure and gastrointestinal upsets.
Shift work can speed the onset of ulcers.
In one study of Italian workers, the time between the start of work and diagnosis of an ulcer was 12 years for day workers, 5.6 years for permanent night workers and 5 years for workers on a rotating eight-hour schedule. In a policy resource and education paper entitled, Circadian Rhythms and Shift Work, Harold Thomas outlined the many biological and social problems associated with rotating shifts. They included a rate of peptic ulcer disease eight times higher than normal, increased cardiovascular mortality, chronic fatigue, excessive sleepiness and difficulty sleeping. Shift workers were likely to increase body weight because of abnormal eating habits and lack of exercise. They had a higher divorce rate, worse rates of substance abuse and depression and were more likely to view their jobs as stressful.