Abstract
OBJECTIVES: Previous meta-analyses have shown that loneliness is associated with poor health (r = -.35) and sleep challenges (r = .29). However, that work is confounded by the inclusion of unhealthy populations, with chronic conditions, such as HIV, Alzheimer's disease, diabetes, and severe mental illness. This pre-registered meta-analysis (PROSPERO CRD42019119135) examined whether loneliness is linked to poorer health in healthy populations. DESIGN: Meta-analysis. METHODS: PsycINFO, ERIC, PubMed, and Web of Science were searched for articles before January 2024 to examine the association between loneliness and health outcomes (categorized as general health, physical health [functional disability], sleep function, sensory acuity, and health service use) for healthy samples. RESULTS: A total of 167 articles (303,643 participants; 334 effect sizes; 158 independent samples) from 36 countries were included in the meta-analysis. Loneliness is associated with worse health for healthy populations (r = -.22), with the largest effect (r = -.23) for general health. Loneliness was not related to health service use for healthy populations. Heterogeneity was substantial, with only 7.2% of the total variance attributable to sampling error, indicating that over 92% of the variability in effect sizes reflected true differences across studies. CONCLUSIONS: Higher loneliness was associated with poorer health for healthy people. There are limited studies using (1) objective measurements of health outcomes in relation to loneliness, and (2) studies exploring the association among young people, highlighting a need for more work in those areas.