Sleeping green: an Italian survey for the assessment of the relationship between sleep and vegetarian diet

Purpose: Plant-based diets are beneficial for health and sleep. Nevertheless, results on the relationship between entirely vegetarian (veg) diets and sleep are scarce and heterogeneous, and many relevant variables are rarely considered. We hypothesize that veg diets may be differently related to several sleep measures considering the role of other intervening factors. Methods: We used an online survey to collect self-reported data about dietary patterns, sleep quality, insomnia symptoms, sleepiness, obstructive sleep apnoea (OSA) risk, and sleep-related movement disorders. Socidemographic variables, adherence to the Mediterranean diet, mental health, eating disorder symptomatology, and chronotype were also considered. Results: Our final sample included 747 participants: 532 omnivores (omniv) and 215 veg. Compared to ominv, veg exhibited a lower risk of OSA, a higher frequency of hypnic jerks, and a lower tendency to eveningness, without differences in sleep quality, insomnia symptoms, sleepiness, and other sleep-related movement disorders. Multiple regression models showed that considering the role of other variables the dietary pattern only predicted OSA risk (i.e., greater OSA risk in omniv) and hypnic jerks (i.e., higher hypnic jerk frequency in veg). Conclusion: Our findings suggest that an utterly veg diet can affect several sleep variables differently, mainly reducing the risk of OSA and increasing the frequency of hypnic jerks. We highlight the relevance of a thorough assessment of sleep measures associated with the veg diet and the importance of controlling for other confounding factors to reach a more nuanced understanding of the relationship between dietary patterns and sleep.