Shu Ling Tan

• Many lifestyle factors can contribute to the deterioration of health. The rise in non-communicable diseases and high-level of stress can result in being less productive at work, shorter lifespans, and a more significant burden on the healthcare system. Therefore, the primary goal of this thesis is to identify the interrelations among multiple health behaviors, and their associations with subjective health, quality of life, and sleep quality. Little is known about sleep as another lifestyle-related health behavior, thus, the second goal is to include sleep as health behavior. As health and engagement in health behaviors vary with age and subjective perspectives, the third goal of this thesis is to investigate age-group differences on multiple health behaviors, and their associations with subjective health, quality of life and sleep quality.This thesis utilized theory-based and empirical investigations based on quantitative questionnaire data. Results suggest that individuals who were physically active were more likely to perceive their health as better, over a period of up to eight years (N=640). Some initial insights were provided regarding how sleep interrelates with physical activity and healthy diets among older adults (N=126). The results further suggest that these multiple health behaviors are associated with increased subjective health, quality of life, and sleep quality, and show significant age group differences (N=790). The findings based on the Compensatory Carry-Over Action Model reflect (1) that carry-over mechanisms of one health behavior may facilitate other health behavior; (2) the understanding of self-regulation of multiple health behaviors in achieving higher-level goals could enhance health and well-being. Adapting lifestyle management with multiple health behaviors, including sleep, may be informative for practical implications of health promotion. Future study should identify the causal pathway of health behaviors and social cognitive factors.