The fact that we see such high levels of loneliness, with substantial divergence across countries, explains why this is an important and active research area. Indeed, there are literally hundreds of papers that have used survey data to explore the link between loneliness, solitude, and health. Below is an overview of what these studies find.

The link between loneliness and physical health

Most papers studying the link between loneliness and health find that both objective solitude (e.g., living alone) and subjective loneliness (e.g., frequent self-reported feelings of loneliness) are correlated with higher morbidity (i.e. illness) and higher mortality (i.e. likelihood of death).

The relationship between health and loneliness can, of course, go both ways: lonely people may see their health deteriorate with time, but it may also be the case that people who suffer from poor health end up feeling more lonely later down the line.

Because of this two-way relationship, it’s important to go beyond cross-sectional correlations and focus on longitudinal studies – these are studies where researchers track the same individuals over time to see if loneliness predicts illness or mortality in the future after controlling for baseline behaviors and health status.

The evidence from longitudinal studies shows that people who experience loneliness during a period of their lives tend to be more likely to have worse health later down the line. In the Netherlands, for example, researchers found that self-reported loneliness among adults aged 55-85 predicted mortality several months later, and this was true after controlling for age, sex, chronic diseases, alcohol use, smoking, self-assessed health condition, and functional limitations. 3

Most studies focus either on subjective loneliness or on objective isolation. However, some studies try to compare both. In a recent meta-analysis covering 70 longitudinal studies, the authors write: “We found no differences between measures of objective and subjective social isolation. read more