Angela B. Clark

Purpose: This study aimed to explore dietary profiles of a night shift working population with overweight/obesity and the impact of different shift work schedules (rotating vs. fixed night) on their diet. Methods: Participants from a randomised controlled trial (SWIFt trial) provided 7-day food diaries at study enrolment. Mean energy intakes (EI), and mean percentage of EI as nutrients (macronutrients, saturated fat, added sugar, alcohol) grams of fibre and milligrams of sodium, were assessed against recommendations for Australian adults. Energy intake was assessed for underreporting. Regression analyses were performed on nutrient intakes whilst controlling for individual and lifestyle factors (age, gender, BMI, physical activity, shift work exposure, occupation and shift schedule). Results: The diet of night shift workers ( N = 245, aged 46.8 ± 9.8 (mean ± SD) years and 53% female) was characterised as high in fat, saturated fat and sodium, while low in carbohydrate and fibre compared with recommendations, regardless of shift work schedule. However, the mean 24 h EI of rotating shift workers was higher than fixed night workers (9329 ± 2915 kJ/day vs. 8025 ± 2383 kJ/day, p < 0.001), even after assessing plausible EI reporters only ( n = 130) (10968 ± 2411 kJ/day vs. 9307 ± 2070 kJ/day, p < 0.001). Furthermore, those performing rotating schedules presented with higher sodium and alcohol consumption. Conclusion: These findings support the evidence of shift work being associated with poorer dietary profiles, which likely contribute towards worsened metabolic health amongst night shift workers. Dietary strategies that target problematic eating habits and address unique challenges of working shift schedules are needed to mitigate metabolic health risk in shift working populations.

Background/Objectives: Shift work and chronotype influence timing and type of food consumed, yet their combined influence is unclear. This study determined differences between temporal patterns of eating (times of first (FEO), last (LEO), and largest eating occasions (LarEO), duration of eating window (DEW), eating frequency) and nutrient intake of night shift workers on and off shift and the additional influence of chronotype. Methods: Participants (46.6 ± 10.2 years, BMI: 33.9 ± 5.6 kg/m², male/female: 57/72) completed work/sleep/food diaries, and the Composite Scale of Morningness. Dietary profiles were characterized by day type as follows: morning shift (MS), 1st night shift (1stNS), subsequent night shifts (SNS), 1st day off after night shifts (1stDONS), or other days off (DO). Results: Across day types, there were significant differences in FEO (p < 0.001), LEO (p < 0.001), LarEO (p = 0.025), DEW (p < 0.001), eating frequency (p = 0.003), total energy (p = 0.022), and fibre intake (p < 0.001). Compared to MS, all night shifts had later FEO, LEO, and LarEO; 1stNS had longer DEW and higher fibre but no differences in frequency, energy, and macronutrient intake. Greater morningness was associated with earlier FEO, LEO, LarEO, and lower %energy from fat and saturated fat. Effect of chronotype on temporal eating patterns was not different across day types; there was a significant, positive relationship between morningness and %energy from carbohydrate (%Energy_CHO) on MS (p = 0.004) and 1stDONS (p = 0.040). Conclusions: Dietary habits of night shift workers vary by shift schedule and degree of morningness. Further studies will confirm if shift schedule is more influential than chronotype on shift workers’ dietary habits.