Plant-based dietary patterns and risk of insomnia: a prospective study

Accumulating evidence suggests that dietary factors may affect sleep, but the associations between dietary patterns and insomnia risk have been poorly explored. The aim of this study was to investigate if plant-based diets are associated with reduced insomnia risks in a cohort study design.

Tzu Chi Health Study participants (N = 5821) recruited from 2007 to 2009 without insomnia were followed until 2018. A traditional classification method (vegetarians vs. non-vegetarians) and a healthful plant-based index (hPDI) were used to define adherence to plant-based dietary patterns. Incident cases of insomnia were ascertained by linking with the National Health Insurance Research Database (NHIRD). Associations between plant-based diets and insomnia were estimated using Cox proportional hazard models.

A total of 464 incident cases of insomnia were identified in the 55,562 person-years of follow up. Insomnia risk was lower in vegetarians when compared to non-vegetarians, hazard ratios (HR) 0.47 (95% CI: 0.27, 0.81) and 0.71 (95% CI: 0.55, 0.91) for males and females respectively. Male participants with the highest hPDI were associated with a significant lower risk of insomnia (HR 0.50 [95% CI: 0.30, 0.85]) when compared to those in the lowest quintile. No association between adherence to hPDI and insomnia in female participants was observed.

Our study showed that vegetarians are associated with a lower risk of insomnia, but there may be sex-specific associations between adherence to hPDI and insomnia risk. These favorable associations are important when considering plant-based diets for their potential additional sleep benefits.