Abstract
BACKGROUND: Electronic sports (esports) are a growing global phenomenon engaging millions of competitive players worldwide. Caffeine is a widely used compound for individuals seeking cognitive enhancement. However, evidence on consumption patterns, motivations, and safety in esports remains limited. We aimed to describe daily caffeine intake among Brazilian esports players and examine associations with competitive level, gaming habits, and adverse effects. METHODS: Cross-sectional study of 181 Brazilian esports players. A 64-item questionnaire captured demographics, gaming habits, and caffeine intake from all dietary sources. We compared amateurs vs semi-professional/professional players and performance-motivated vs other motivations, and examined dose-response using intake categories (≤100, 101-300, 301-600, >600 mg/day) and correlations for continuous variables. RESULTS: Median 168 mg/day (IQR 52-402; mean 280 ± 316); coffee was the main source (72.2% of total), and 55.8% consumed energy drinks, contributing 14.0% of intake. Overall, 25.7% exceeded 400 mg/day (46/179); intake did not differ between competitive levels (Amateur 172 vs Semi-Pro/Pro 121 mg/day; p = 0.387). No correlation with gaming hours (ρ = 0.068; p = 0.369). Under the primary positivity rule (≥"occasional"), adverse effects were common among respondents with symptom frequency data: any adverse effect 76.5%, insomnia 45.2%, tachycardia 29.1%, stomach pain 45.5%, tremors 23.7%. Linear trend tests across dose categories were not significant (any 0.822; insomnia 0.530; tachycardia 0.905; stomach pain 0.409; tremors 0.877), and per-category effect sizes were small (r-trend ≈ 0.01-0.08; OR per +1 category ≈ 0.89-1.16). Comparing >300 vs ≤300 mg/day for any adverse effect yielded OR 1.38 (95% CI 0.56-3.45). Performance-motivated players (12.6%) consumed more (+89 mg/day; p < 0.001). Using caffeine to combat fatigue (56.0%) was associated with higher insomnia (OR 2.50; 95% CI 1.37-4.55; q = 0.004). Notably, insomnia was common (45.2%), underscoring applied relevance. CONCLUSIONS: Brazilian esports players show moderate caffeine intake, mainly from coffee. Adverse effects were common, although linear dose-response across intake categories was not observed; the observed fatigue-caffeine cycle highlights the need for practical guidance on timing and source awareness, alongside sleep-hygiene strategies, to support sustainable performance.