The nutritional and metabolic impact of night shift work in a real-world setting

BackgroundGrowing evidence from large epidemiological and small lab-controlled studies links night shift work to impaired sleep, cognitive performance, and cardiometabolic health, but evidence from real-world occupational environments remains limited. MethodsNutritional intake and cardiometabolic parameters were assessed using multiple wearable devices and mobile health apps, alongside other objective and subjective assessment tools among shift workers during three consecutive night shifts and three consecutive day shifts. ResultsOf 72 participants, 96% were healthcare workers, 82% were female, with a median age of 31 years and a median body mass index 22.7 Kg/m2. Night shifts led to poorer cognitive performance and sleep quality with higher levels of fatigue (all p<0.01). While intake of calories, protein, and fat was reduced during night shifts (all p<0.05), glycemic variability and postprandial glucose spikes were increased compared to day shifts (all p<0.05). After three consecutive night shifts, the morning systolic blood pressure was elevated, plasma cortisol was reduced (both p<0.05), and the 24-hour heart rate and heart rate variability were altered, indicating disrupted parasympathetic function. Exploratory analysis revealed higher protein intake correlated with lower glycemic variability (p<0.01), whereas nighttime eating was associated with increased glycemic variability (p<0.05). ConclusionNight shift work is associated with adverse cardiometabolic health. Future interventional studies could target meal composition and meal timing to improve glycemic variability in night shift workers. Trial RegistrationClinicalTrials.gov NCT05177965