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Head-to-head evidence comparison — which supplement is right for you?
Caffeine wins 3 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
29 of 35 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both Caffeine and Modafinil have evidence — compare verdict strength side-by-side.
100-200mg
Morning, 30-60 minutes before exercise
Pill/capsule for precise dosing
Approved dosing is 200 mg once daily in the morning for narcolepsy and OSA, or 200 mg taken ~1 hour before the start of a night shift for shift-work sleep disorder. A prescription drug; off-label cognitive use is not an approved or standardized regimen.
morning
Oral tablet (modafinil)
15-45 minutes
30-60 minutes
30-60 minutes
30-60 minutes
Hours (per dose); weeks for steady benefit
Per dose (acute)
Acute
Throughout use
Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis
Nutrients (2020) · Meta analysis · n=2020
A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials
Critical reviews in food science and nutrition (2019) · Meta analysis · n=606
Thirteen RCTs with 606 participants were included in the meta-analyses.
Effect of Caffeine and Nitrates Combination on Exercise Performance, Heart Rate and Oxygen Uptake: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=95
The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
Randomized trial of modafinil for the treatment of pathological somnolence in narcolepsy. US Modafinil in Narcolepsy Multicenter Study Group.
Annals of neurology (1998) · Rct · n=283
Pivotal placebo-controlled, double-blind, 18-center RCT in 283 narcolepsy patients (modafinil 200 or 400 mg vs placebo)
Randomized trial of modafinil as a treatment for the excessive daytime somnolence of narcolepsy: US Modafinil in Narcolepsy Multicenter Study Group.
Neurology (2000) · Rct · n=271
Second pivotal 9-week, placebo-controlled, double-blind, 21-center RCT (n=271; 200 or 400 mg vs placebo)
Modafinil for excessive sleepiness associated with shift-work sleep disorder.
The New England journal of medicine (2005) · Rct · n=209
3-month double-blind RCT of 200 mg modafinil before each night shift vs placebo in 209 shift-work-sleep-disorder patients (NEJM)
Based on multiple meta-analyses showing 3-6mg/kg optimal dosing. Performance benefits plateau around 200-300mg with increased jitteriness at higher doses.
AI-estimated from published studies. Interpret as directional guidance.
Caffeine has a higher evidence score (9.5/10 vs 5/10) and wins in 3 of 3 categories.
No known interactions between Caffeine and Modafinil have been documented in our database. However, always consult a healthcare provider before combining supplements.