**Background:** Ramadan fasting (RF) is observed by approximately 1.5 billion Muslims worldwide and involves complete abstinence from food, drink, and smoking from dawn to sunset for 29–30 consecutive days. Sleep is known to be significantly altered during Ramadan, with previous studies reporting delays in bedtime and waking time and reductions in total sleep time. Diet quality, timing, and quantity have been shown to impact sleep duration and quality outside of Ramadan, but the relationship between dietary and lifestyle changes during RF and sleep outcomes across diverse cultural contexts had not been adequately studied.
**Methods:** This cross-sectional study collected data using a structured, self-administered electronic questionnaire translated into 13 languages and disseminated to Muslim populations across 27 countries. Data collection occurred from May 10 to June 10, 2021 (during Ramadan and shortly after). Inclusion criteria were adult Muslims (≥18 years) who observed RF. Exclusion criteria included those diagnosed with or treated for a mental health problem, individuals following specific diets, and shift workers. A total of 28,179 participants were recruited; after applying exclusion criteria, 24,541 participants were included in the final analyses. The questionnaire assessed dietary intake (20 food items and beverages), eating habits, physical activity (PA), smoking, computer use, and three sleep parameters (sleep duration, sleep quality, and sleep disturbance). Structural equation modeling (SEM) was performed using Smart PLS 3 software to examine how dietary and lifestyle factors affected sleep parameters. Discriminant validity was assessed using the Heterotrait-Heteromethod ratio of correlations (HTMT), and multicollinearity was evaluated using variance inflation factor (VIF) statistics (all VIF values <5.0).
**Key Results:** The study population comprised 19,355 participants from the MENA region, 3,580 from South Asia, and 1,606 from Southeast Asia. Females comprised approximately two-thirds of participants, and the most common age group was 18–32 years. SEM analysis revealed that optimal sleep duration (7–9 h) was significantly associated with sufficient physical activity (B = 0.05, p = 0.001) and sufficient consumption of plant-based proteins (cereals, pulses/dried legumes, bakery products) (B = 0.04, p = 0.001). Frequent ordering of food delivery was also positively associated with sleep duration (B = 0.02, p = 0.001). Smoking was significantly associated with lower self-evaluated sleep quality (B = -0.01, p = 0.001) and greater sleep disturbance (B = 0.03, p = 0.001). Better sleep quality was associated with sufficient PA (B = 0.05, p = 0.001), sufficient consumption of vegetables, fruits, and dates (B = 0.01, p = 0.001), and sufficient plant-based proteins (B = 0.04, p = 0.001). Infrequent consumption of delivered food was associated with better sleep quality (B = 0.02, p = 0.001). Frequent computer use was associated with lower sleep disturbance (B = -0.04, p = 0.001). Unexpectedly, sufficient PA, consumption of vegetables/fruits/dates, plant-based proteins, and animal-based proteins were positively associated with sleep disturbance, though effect sizes were weak. The coefficient of determination (R²) values were 0.01 for sleep duration, 0.02 for sleep quality, and 0.02 for sleep disturbance (all p < 0.001). Significant regional differences were found across all dietary and lifestyle behaviors except for food delivery consumption.
**Clinical Implications:** This large-scale multinational study provides evidence that modifiable dietary and lifestyle factors are associated with sleep outcomes during Ramadan fasting. Increasing intake of fruits, vegetables, and plant-based proteins, engaging in regular physical activity, avoiding smoking, reducing consumption of delivered foods, and limiting screen time may help improve sleep quality and duration during Ramadan. These findings are particularly relevant given that sleep disruption during Ramadan is common and may have implications for metabolic health, circadian rhythm regulation, and overall well-being. Healthcare providers counseling Muslim patients who observe Ramadan fasting should consider recommending these evidence-based dietary and lifestyle modifications to support healthy sleep. However, the cross-sectional design precludes causal inference, and the study was conducted during the COVID-19 pandemic, which may have influenced habitual behaviors. Future longitudinal and interventional studies are needed to confirm these associations and establish causality.