Circadian disruption and health: can diet play a protective role?

This thesis investigates how dietary intake modifies the adverse metabolic effects of circadian disruption, specifically social jet lag (SJL), the misalignment between an individual's biological clock and their socially imposed sleep schedule. Focusing on glucose homeostasis and adiposity, the research demonstrates that in populations experiencing SJL, such as night shift workers, consuming a high-glycemic index (GI) meal significantly increases glycemic variability, and the resulting glucose excursions were found to impair sustained attention. In contrast, a low-GI meal offered a beneficial alternative to fasting. A longitudinal study further established a direct link between high SJL (≥2.09 hours) and a 45% increased risk of developing type 2 diabetes (T2D), a relationship partially mediated by dietary patterns, particularly those high in fruits and vegetables. Employing Mendelian randomization to assess causality, the analysis revealed that while chronotype-related factors did not directly influence breakfast skipping, frequent breakfast consumption itself was associated with healthier overall dietary habits. Notably, specific components of this diet, such as total fat intake, were subsequently linked to glucose control. In summary, the findings emphasize that practical dietary strategies, such as choosing low-GI foods during night shifts and adopting a plant-rich diet to mitigate the effects of SJL, can significantly counteract the associated metabolic risks, offering valuable insights for the general population.