Association Between Dietary Phytochemical Index, Inflammation and Oxidative Stress With Sleep Duration and Sleep Quality in Iranian Adults Publisher Pubmed



Balali A ; Poursalehi D ; Shahdadian F ; Rouhani P ; Saneei P
Source: Scientific Reports Published:2026

Abstract

We aimed to explore the link between dietary phytochemical index (DPI) and sleep quality/duration, along with oxidative stress and inflammatory biomarkers in Iranian adults. The present cross-sectional investigation was carried out on 535 adults (54% male) with a mean age of 42.6 years. Sleep quality and duration were assessed using the Pittsburgh Sleep Quality Index, and dietary intake was evaluated using a 168-item food frequency questionnaire. DPI was calculated as a percentage of energy intake derived from phytochemical-rich foods. An overnight fasting blood sample was collected from each participant to evaluate serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX), and high-sensitivity C-reactive protein (hs-CRP) levels. Participants in the third tertile of DPI had 43% lower odds of having short sleep duration (OR = 0.57, 95%CI: 0.32–0.99) and 53% lower odds of having poor sleep quality (OR = 0.47, 95%CI: 0.26–0.86). Regarding specific domains of poor sleep quality, an inverse association was observed between sleep latency (OR = 0.39, 95%CI: 0.17–0.89) and sleep disturbances (OR = 0.40, 95%CI: 0.16–1.02). Higher scores of DPI were associated with marginally lower odds of having short sleep duration in overweight/obese individuals (OR = 0.55, 95%CI: 0.27–1.09) and males (OR = 0.42, 95%CI: 0.18–1.01). A significant inverse relationship was observed between DPI and having poor sleep quality in normal-weight subjects (OR = 0.20, 95%CI: 0.06–0.74) and females (OR = 0.40, 95%CI: 0.17–0.94). A marginally inverse association was observed between each tertile increment in DPI and hs-CRP levels (B (non-standardized β) =-0.31 mg/L, 95%CI: -0.64, 0.01; P = 0.06). Individuals with good quality of sleep also had lower serum levels of MDA than those with poor quality of sleep (162.0 vs. 185.5 nmol/mL; P = 0.01). However, no significant association was observed regarding SOD, GPX, and hs-CRP levels and sleep quality. Iranian adults with higher DPI scores had lower odds of having short sleep duration and poor sleep quality. MDA and hs-CRP might be intermediate factors for this association. © The Author(s) 2026.