The associations between shift work exposure and selected health outcomes in the Canadian Longitudinal Study of Aging

We live in a globalized 24-hour society, consuming services, products and entertainment around the clock. As a result, more and more people are working in shifts. Currently, one in every fourth Canadians is working in shifts other than regular daytime hours. At the same time, the number of senior shift workers is growing in most developed countries, including Canada, due to the general aging of the working population. Together with physiological and epidemiological data on the alarming relationships between shift work and various physical, social and mental health outcomes, there is reason to believe that shift work may become a major occupational health problem in the near future. This study will analyze cohort data from the Canadian Longitudinal Study on Aging (CLSA) to investigate the associations between shift work and three specific outcomes related to health of middle-aged and older adults i.e. variations in age at natural menopause, frailty and cognitive functions.

The dissertation investigated the associations between shift work and three specific outcomes related to the health of middle-aged and older adults. The primary exposure, shift work, was measured using three derived variables: ever exposed to shift work, shift work exposure in the current job, and shift work exposure in the longest job. The results of the first study discovered that shift work, in particular rotating shift work, significantly influenced the timing of natural menopause. Overall, being exposed to shift work was significantly associated with the later onset of menopause. Moreover, the study findings suggested that women who worked as a rotating shift worker in their current job or in their longest job were significantly related to the delayed onset of menopause. Results of the second study revealed that being exposed to shift work was significantly associated with frailty at three years of follow-up. Particularly, exposure to rotating shift work during the longest job among females was significantly related to frailty. Finally, the third study found that exposure to night shift work (both the current and longest job) was associated with overall cognitive impairment. In terms of domain-based measures, night shift work (the longest job) was associated with memory function impairment, and those exposed to rotating shift work (both the current and longest job) showed impairment on executive function measures when compared to daytime workers.