Planetary Health Diet, Obesity and Sleep Quality in Italian Adults

Background/Objectives: Sleep and diet have been demonstrated to be interconnected factors playing an important role in human health. However, the relationship between sustainable dietary patterns, sleep, and obesity remains to be fully elucidated. This study investigated the association between adherence to the Planetary Health Diet (PHD) and sleep quality among Italian adults, while also exploring the potential role of weight status in this relationship. Methods: This observational study included 1936 Italian adults. Dietary intake was assessed using a validated food-frequency questionnaire (FFQ), and adherence to the PHD was evaluated using a validated index. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Multivariable logistic regression analyses were conducted to examine the associations between PHD adherence and sleep quality. Results: Among 1936 participants, higher PHDI adherence was associated with greater odds of adequate sleep quality. Compared with the lowest quartile, participants in the highest PHDI quartile had 65% higher odds of adequate sleep quality (OR: 1.65; 95% CI: 1.20, 2.28); significant associations were also observed for sleep disturbance and self-rated sleep quality, whereas sleep duration, sleep efficiency, and sleep-medication use were not associated with PHDI adherence. Associations were more pronounced among participants with overweight or obesity, in whom the highest quartile was associated with more than twice the odds of adequate sleep quality (OR: 2.40; 95% CI: 1.46, 3.95). Additional domain-specific associations were observed in this subgroup, whereas no significant association with overall sleep quality was found among normal-weight participants. Conclusions: Greater adherence to the PHD was associated with better overall and self-rated sleep quality among Italian adults, with stronger associations observed among individuals with overweight or obesity. These findings suggest that adherence to a healthy and sustainable dietary pattern may be related to better sleep health, particularly among individuals with excess body weight.