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Thesis Format

Integrated Article


Master of Science


Epidemiology and Biostatistics


Saverio, Stranges.

2nd Supervisor

Speechley, Mark.



Sleep health is a latent construct comprising various sleep measures such as duration, quality, initiation, maintenance, and daytime sleepiness. This thesis compared the association of two measures of sleep health, a conventional summary score and a pooled index, with incident multimorbidity over a 3-year follow-up in 30,097 middle- to older-aged adults from the Canadian Longitudinal Study on Aging. At baseline, approximately 26% and 29% of participants with multimorbidity displayed poor sleep patterns according to additive and pooled indexing methods. Longitudinal analysis indicated that those with additive scores of 4 to 5 at baseline had a 1.54 (95% CI: 1.18, 2.03) higher odds of multimorbidity compared to those with a score of 0, whereas 1-unit increases in pooled scores were associated with 1.32 (95% CI: 1.19, 1.47) odds after controlling for relevant confounders. Future research is suggested to understand the association better and inform public health and clinical guidelines.

Summary for Lay Audience

Sleep problems affect a large segment of older adults in Canada and globally and contribute to an increased risk of chronic disease yet, are often neglected as a public health concern. Older adults are also more likely to develop multimorbidity, the co-occurrence of multiple chronic conditions. Emerging research has shown that sleep problems, similar to unhealthy diet or physical inactivity, may represent a modifiable behavioural risk factor that if improved could help lower the risk of multimorbidity in older adults. Sleep is often measured in terms of how long we sleep or how refreshed we feel in the morning, and then analyzed as separate components of sleep rather than together as overall ‘sleep health’. A better understanding of sleep and its effect on health may come from examining sleep health, a concept that comprises these various facets of sleep into one holistic measure. The thesis aims to construct an index to measure sleep health, and then use this index to examine the association between sleep health and multimorbidity over time. The first study explored which sleep variables should be included in the index and compared two different methods of index development. The performance of these indices was compared to individual sleep measures by estimating the proportion of participants with multimorbidity experiencing poor sleep health. In the second study, a longitudinal analysis was conducted using the two indices to examine the association between sleep health and multimorbidity over time. The results revealed a significant relationship between poorer sleep scores and the development of multimorbidity, even after accounting for other health and lifestyle factors. A comparison of the two indices showed that the pooled indexing method performed better, particularly after age and sex stratification. These findings have practical implications for the health of Canadians by informing lifestyle changes and clinical interventions that may improve sleep health and thereby reduce the occurrence and burden of chronic conditions.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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