Purpose in life, sleep, and loneliness in later life : a cross-sectional study of older New Zealanders : a thesis presented in partial fulfilment of the requirement for the degree of Master of Science in Health Psychology, School of Psychology, Massey University, New Zealand

Abstract

Background: Loneliness and sleep issues are increasingly prevalent in older adults and negatively affect their physical, mental, psychosocial health and well-being. In New Zealand (NZ), one in four people is projected to be aged 65 years or older by 2050. This unprecedented demographic shift presents significant challenges for social support and healthcare systems, particularly as older adults become more vulnerable due to physical decline, retirement and bereavement. Despite growing concern, limited research examines how sleep and loneliness interact to influence later life outcomes. There is evidence suggesting that purpose in life (PiL defined as a meaningful direction or goal that motivates and guides human behaviour) may help individuals adopt healthy behaviours (e.g., sleep), engage in social participation, and enhance emotional well-being, including loneliness. The present study investigates the relationship between PiL and loneliness, and tests whether sleep health mediates this relationship. Methods: Analyses were conducted of data from the 2022 NZ Health, Work and Retirement Study, which included 5,514 older adults aged between 55–93 years. Bivariate analyses examined associations between loneliness (scored on the De Jong Gierveld Scale), PiL (Life Engagement Test), sleep status (self-reported duration and satisfaction), and key sociodemographic and health variables. Multivariate regression was used to identify independent predictors of loneliness. Mediation analyses tested whether sleep quality or duration mediates the relationship between PiL and loneliness. Results: Poor sleep outcomes were associated with increased scores on the loneliness scale. PiL, mental health, socioeconomic status (SES), age, living arrangement, ethnicity, and gender were all independently associated with loneliness. For example, a 1-point increase in PiL test corresponded to a 0.85-point decrease in loneliness score. Sleep satisfaction partially mediated the relationship between PiL and loneliness, such that individuals with higher PiL were more likely to report greater sleep satisfaction, which, in turn, contributed to less lonely. The mediation effect of sleep duration was statistically significant but negligible. Conclusion: The present study supports prior research findings that higher levels of PiL are associated with reduced levels of loneliness. This thesis contributes to the literature by highlighting the mediating role of sleep in this relationship. These findings will inform future research examining the interactions between psychosocial well-being and sleep health, as well as guide practices that build and maintain PiL, promote sleep health, and combat loneliness, enabling older adults to age with purpose and independence.