Introduction
Some studies are available on the alarming rate of overweight and obesity among college students1-4. The majority of college students do not regard the dietary and physical activity guidelines, indicating the necessity of prevention treatments and increased understanding of overweight in college students2. In addition to the high prevalence of overweight and obesity among college students, lack of sleep quality is also a prevalent occurrence among this population which has affected 10% to 50% of this population5,6 lack of sleep quality have profound effects on students’ health (including increased risk of chronic diseases), quality of life, mood, and daytime function7,8. Lack of sleep quality similar to obesity, is associated with increased circulatory levels of pro-inflammatory markers and consequent insulin resistance and orexin decline9. Orexin is essential for the stability of sleep/wake states in various species, namely dog, mouse, and human10. Orexin knockout mice have exhibited frequent sudden collapses during the dark phase, the portion of the circadian rhythm during which there is the most time awake and spent in the activity. These attacks resemble human cataplexy attacks11. Orexin neuron activity is suppressed by Tumor Necrosis Factor- alpha (TNF-α) through this cytokine degrading the mRNA of orexin precursor in a time- and dose-dependent manner12,13.
Observational studies showed an independent association between the lack of sleep quality and elevated high-sensitivity C-Reactive Protein (hs-CRP), but this relationship was gender-specific in some studies14-17. Vgontzas and colleagues found that two hours of sleep reduction per night for seven nights led to increased TNF-α in healthy men but not women, but increased Interleukin 6 (IL-6) in both men and women18. In sum, sleep restriction leads to a systemic increase of the inflammatory mediators that may have prognostic significance for metabolic diseases.
Literature has supported diet represents an essential role in the modification and regulation of low-grade chronic inflammation19,20. So, it has been confirmed that Western dietary patterns have pro-inflammatory potential, and contrarily healthy dietary patterns such as the Mediterranean diet are related to anti-inflammatory status21. Dietary patterns have been shown to influence inflammatory pathways; for instance, adherence to healthy dietary patterns such as the Mediterranean diet and/or national dietary guidelines can decrease inflammation and the Mets22.An umbrella meta-analysis of studies found promising evidence about the significant benefits of the Mediterranean diet in lowering body weight, Body Mass Index (BMI) and Waist Circumference (WC) as well as the improvement of lipid profile versus the control diets4. Okun et al. showed that young and healthy women with a poor sleep had more circulatory levels of C-Reactive Protein (CRP) compared to women with better sleep quality. The authors supposed that this pro-inflammatory status may increase the risk of various diseases that affect women, such as polycystic ovary syndrome and preeclampsia. However, they couldn’t find any significant association between sleep duration and inflammatory markers23. The results of the National Health and Nutrition Examination Survey of (NHANES) 2005-2006 among 2051 adults (≥20 years) indicated that having regular physical activity and not smoking and healthy eating and enough sleep were the two health behavior pairs related to lower systemic inflammation24. In this regard, the Dietary Inflammatory Index (DII®) was designed to assess the inflammatory potentials of the individuals ‘diet. It was proven that this index could predict inflammation-related health status in any population25. Two review studies concluded that the DII score appears to be a beneficial tool to assess the dietary inflammatory capacity and to perceive further the correlations between diet, inflammation, and chronic metabolic diseases such as obesity, diabetes, and Cardiovascular Diseases (CVD)26-28.
Overweight, obesity and lack of sleep quality as inflammatory states are the common problems among college students and the association of DII with these problems among this population is unknown28. It was hypothesized that a diet with a higher inflammatory potential could be associated with obesity and poor sleep in Iranian female students.