Grant: Master's Award: Canada Graduate Scholarships

In 2007, shift work was classified as a lifestyle behavior which could probably cause cancer. In fact, there is evidence that light at night during shift work may increase the chance of breast cancer, through changing melatonin concentrations in the body. Melatonin is a hormone which is thought to be an anti-cancer agent which acts through its antioxidant activities and its ability to control the concentration of another hormone estrogen. Although melatonin has been identified as a potential intermediate, scientific studies which have used absolute melatonin concentrations to assess its connection to light at night have not been convincing. Instead, examining the melatonin secretion pattern may be a more appropriate measure in relation to light at night. By applying a statistical method known as ‘cosinor analysis’, the variation in the melatonin concentrations among female hospital workers will be identified. Additional assessment of sleep quality will help further elucidate this circadian disruption. The specific objectives of the proposal are to 1) look at variations in melatonin concentrations when comparing between shift work status and 2) to describe how shift work status is linked to the variation in melatonin concentrations. This study will be conducted on 300 female hospital workers from Kingston General Hospital and Hotel Dieu. More specifically, they will be recruited from inpatient units, and laboratory, diagnostic and support services of these hospitals. Classification of shift work status will be done through interview. Furthermore, over each 8-day study period, data was collected on melatonin concentrations and sleep quality. The significance of this study will help increase the understanding of the impacts of shift work. Such knowledge is necessary in the health care profession, as it will lead to healthier workplace policies and better disease prevention measures.