Rotating shift workers eat more, but diet inflammation scores match daytime workers

Men working rotating shifts at a defense industry factory in Ankara, Türkiye, consumed more energy and more fat, cholesterol and several micronutrients than colleagues on fixed daytime schedules, yet the inflammatory potential of their diets did not differ significantly between the two groups, according to a cross-sectional study of 52 male workers. The research, led by Şeyma Sünbül and Perim Fatma Türker, set out to compare the Dietary Inflammatory Index (DII), sleep quality, dietary intake and body measurements between fixed daytime and rotating shift workers and to test how these parameters relate to one another. The team assessed what each participant ate using 24-hour dietary recalls collected on three non-consecutive days, from which macronutrient and micronutrient intakes were calculated. DII scores were computed to gauge the inflammatory potential of each diet, sleep quality was evaluated with the Pittsburgh Sleep Quality Index (PSQI), and the researchers measured anthropometrics, body composition, blood pressure and biochemical parameters including fasting plasma glucose, total cholesterol, HDL-C, LDL-C, triglycerides, C-reactive protein and homocysteine using standardised protocols.

Rotating shift workers had significantly higher total energy intake and higher daily intakes of fructose, total fat, saturated and monounsaturated fatty acids, and cholesterol than fixed daytime workers, along with higher intakes of vitamin A, folate, iron, calcium and phosphorus (p < 0.05). Despite these dietary differences, mean DII scores did not differ significantly between the groups: fixed daytime workers averaged 0.2 ± 1.86, while rotating shift workers averaged −0.2 ± 2.25.

When the researchers examined how the DII related to sleep, they found that DII scores were positively correlated with the global PSQI score (r = 0.278, p = 0.046), meaning higher dietary inflammatory potential went hand in hand with poorer overall sleep quality across the sample. The DII also correlated positively with two PSQI components: the sleep duration component score (r = 0.319, p = 0.021) and the daytime dysfunction component score (r = 0.287, p = 0.039). However, the association between the DII and overall sleep quality was no longer statistically significant after the researchers adjusted for potential confounding factors, namely age, body mass index, smoking status, physical activity and work schedule. This statistical adjustment matters because it suggests the raw link between pro-inflammatory eating patterns and poor sleep may partly reflect other characteristics of the workers rather than an independent relationship.

The study’s design also limits how broadly the findings apply. With 52 male participants from a single factory and a cross-sectional snapshot rather than follow-up over time, the results describe associations at one point in time and cannot establish that diet causes poor sleep or the reverse. The all-male sample and single workplace further restrict generalisability to other populations.

Within those limits, the authors interpret their results as evidence that dietary habits, pro-inflammatory dietary patterns and poor sleep quality may represent co-existing factors associated with metabolic risk in this workforce. Shift work is already associated with irregular eating behaviors, increased energy intake and impaired sleep quality, and poor dietary patterns may elevate systemic inflammation, contributing to long-term metabolic and cardiovascular risks. Addressing these overlapping factors, the researchers suggest, may contribute to better overall metabolic health among shift workers.

Subject of Research: Associations among the Dietary Inflammatory Index, sleep quality and nutritional status in fixed daytime and rotating shift workers

Article Title: Association among Dietary Inflammatory Index, sleep quality and nutritional status in fixed daytime and rotating shift workers

Article References: Sünbül, Ş., & Türker, P. F. (2026). Association among Dietary Inflammatory Index, sleep quality and nutritional status in fixed daytime and rotating shift workers. PLOS One, 21(10), e0360075. https://doi.org/10.1371/journal.pone.0360075

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360075

Keywords: Dietary Inflammatory Index, shift work, sleep quality, Pittsburgh Sleep Quality Index, rotating shifts, nutritional status, cross-sectional study, metabolic risk, dietary intake, inflammation, Association, Dietary