Loneliness is a common emotional distress experience and there is increasing evidence of associations with unhealthy lifestyle and adverse health-related factors. Little is known about age and sex as potential effect modifiers, and about the prevalence of loneliness.

To assess the associations of loneliness with behavioral, physical and mental health factors, taking sex and age into account and to examine the prevalence of loneliness in individuals aged 15+ years.

Data from 20,007 participants of the cross-sectional population-based Swiss Health Survey 2012 were analyzed. The association of loneliness with lifestyle and health-related factors were assessed with logistic regression analyses. Wald tests were used to test for age and sex differences.

Loneliness was reported by 64.1% of individuals, and was associated with smoking (OR 1.13, 95% CI 1.05–1.23), physical inactivity (1.20, 1.10–1.31), non-adherence to the 5-a-day recommendation for fruit and vegetable consumption (1.21, 1.07–1.37), and more visits to a physician within the last year (1.29, 1.17–1.42). Loneliness was also associated with high cholesterol levels (1.31, 1.18–1.45), diabetes (1.40, 1.16–1.67), self-reported chronic diseases (1.41, 1.30–1.54), impaired self-perceived health (1.94, 1.74–2.16), moderate and high psychological distress (3.74, 3.37–4.16), and depression (2.78, 2.22–3.48). Age modulated the associations in BMI, smoking, visiting a physician within the past year, and self-perceived health. Sex did generally not modulate the associations.

Loneliness is associated with unhealthy lifestyle, and poorer physical and mental health. Associations were modulated by age, but not sex. Further longitudinal studies are needed to elucidate the causal relationships of these associations.

The authors have not supplied their declaration of competing interest.