Modafinil vs caffeine: what head-to-head trials show

Key points

• In sleep-deprived healthy adults, small trials found modafinil and caffeine about equally effective at restoring vigilance for a few hours. The 2002 authors concluded modafinil “does not appear to offer advantages over caffeine” [3].
• Differences that did appear concerned duration and side effects, not strength: caffeine’s effect faded sooner, and in one trial modafinil was ahead on vigilance eight hours after dosing [6][9].
• In rested adults the evidence is thinner. One 48-man pilot found a caffeine effect on sustained attention and none for modafinil [12].
• Caffeine is a food ingredient; modafinil is a Schedule IV prescription drug in the US and restricted to narcolepsy in the EU [1][2][18][19].
• The tier-list claim that coffee outranks modafinil is partly supported, but no trial ranks them.

What is being compared, and what is not

This article covers evidence comparing the two drugs, directly and indirectly. It gives no doses and no advice. For what modafinil is approved for, see the modafinil guide; for its effects in rested people, the healthy adults evidence review.

None of the trials measured everyday cognitive enhancement. They measured alertness and performance in a laboratory, mostly after one dose. We did not find a meta-analysis that pools modafinil-versus-caffeine trials.

The direct comparison trials

Doses are left out on purpose. They were fixed by each protocol and differed between trials, which matters for interpretation (see limits below).

Study	Size and design	Condition	Measured	Result	Funding
Wesensten 2002 [3]	50 healthy young adults; 5 parallel groups of 10 (placebo, three modafinil doses, caffeine); double-blind	Awake 54.5 h; dosed after 41.5 h	Performance and alertness tests, hourly	The two higher modafinil doses beat placebo, comparable to caffeine; gains largest 6 to 10 a.m. Few side effects (nausea, heart pounding)	Not stated in the abstract; full text not opened
Wesensten 2004 [4]	Same 50 participants, secondary analysis	Same	Time-on-task fatigue on a 10-minute vigilance test	One modafinil dose and caffeine attenuated fatigue similarly; a lower modafinil dose worked for a shorter time	Not stated in abstract
Wesensten 2005 [5]	48 adults; 12 per group (placebo, caffeine, d-amphetamine, modafinil)	Awake 85 h; dosed after 64 h	Psychomotor vigilance, objective alertness, executive tasks	All three improved vigilance and alertness for about 2 to 4 h; executive-task results mixed	Not stated in abstract
Killgore 2008 [6]	53 adults; groups of 11 to 16	Dosed after 44 h awake	Psychomotor vigilance; side effects; recovery sleep	All three equally effective; caffeine’s action shortest; caffeine had the most reported side effects, modafinil did not differ from placebo	Not stated in abstract
Killgore 2009 [7]	54 adults; 12 caffeine, 12 modafinil, 16 dextroamphetamine, 14 placebo	45 to 50 h awake	Tower of London, Tower of Hanoi, Wisconsin Card Sorting	Modafinil better on two planning/perseveration measures, caffeine on Tower of Hanoi: no drug won across tasks	“Not an industry supported study”; one author a part-time US Army contract researcher, another owns a consulting business
Dagan 2006 [8]	Within-subject, counterbalanced; sample size not in abstract	Sustained wakefulness at night	Flight-simulator performance, temperature, blood pressure	Equal effect; lower doses than earlier trials	Not stated; abstract only
Wingelaar-Jagt 2023 [9]	32 Royal Netherlands Air Force volunteers; double-blind crossover, three test days	Awake a median 17 h	Vigilance and tracking, psychomotor vigilance, sleepiness scale	Both beat placebo on nearly all endpoints; modafinil better than caffeine on vigilance and sleepiness at 8 h	Dutch Ministry of Defence; no competing interests declared
Zhong 2024 [10]	Double-blind within-subject pilot, three sessions; size not in abstract	36 h awake	Resting-state fMRI; subjective sleepiness	Neither drug differed from placebo on sleepiness; connectivity changed in different thalamic regions	Not stated; abstract only
ERP study 2026 [11]	14 healthy men; double-blind crossover	36 h awake	2-back task, event-related potentials	Modafinil improved accuracy past baseline; caffeine held it at baseline; brain signals differed	Not stated; abstract only
Repantis 2021 [12]	48 healthy men, rested; randomized, double-blind, placebo-controlled, three stimulant arms (also methylphenidate)	No sleep loss	Test battery 90 min after dosing; memory at 24 h	Caffeine: sustained attention. Modafinil: no significant effect. Authors: pilot, too small for small effects	Volkswagen Foundation grant, funder had no role; no competing interests
Franke 2017 [13]	39 male chess players; 4-way crossover	Rested	Twenty 15-minute games against software	All three slowed play and raised games lost on time; after excluding those, modafinil and methylphenidate scored higher, caffeine did not	Europe PMC lists a Mainz university psychiatry department; full text not opened

We read only three of the ten in full (Killgore 2009, Wingelaar-Jagt 2023, Repantis 2021); the others from abstracts, so funding for them is unverified. The 2023 Dutch trial found a subgroup effect: pilots who were more fatigue-vulnerable on placebo responded differently to the drugs [24].

What the pattern suggests, and what it cannot show

The sleep-deprivation trials point the same way: both drugs help, neither clearly beats the other on short-term vigilance. Wesensten’s 2005 team wrote that the benefits last for different lengths of time “in accordance with the different elimination rates” [5].

Three cautions apply. Groups of 10 to 16 can show that two drugs are not wildly different, not that they are equivalent. Executive-function results flip between tasks [7]. And a 2025 systematic review of seven studies in military pilots found caffeine and modafinil the most effective short-term countermeasures, yet neither fully restored baseline performance in severe sleep deprivation [15].

In rested people, pooled modafinil effects against placebo are small: g = 0.10 across 19 trials, SMD 0.12 across 14 [16][17]. A narrative review reports caffeine improves alertness, vigilance and reaction time but acts less consistently on memory and executive function [14]. These are different reviews of different studies, so the numbers cannot be set side by side.

How they work

Caffeine “exerts its effects by blocking adenosine receptors” [14]. Modafinil’s mechanism is, per its label, “unknown”. In vitro it binds the dopamine transporter and inhibits dopamine reuptake, and mice lacking the transporter showed no wake-promoting effect, but rats’ response was not blocked by a dopamine antagonist the way amphetamine’s was, and the label says it is “not a direct- or indirect-acting dopamine receptor agonist” [1]. The two small brain-activity studies above found distinct patterns, which fits different mechanisms but does not explain them [10][11].

Onset, duration and side effects

The modafinil label gives peak blood levels at 2 to 4 hours, about an hour later with food, and an effective half-life of about 15 hours after repeated dosing [1]. The authors of the 2023 trial give caffeine’s peak as 30 to 120 minutes and half-life as 4 to 6 hours, citing other papers [9]. In the Dutch trial both drugs improved vigilance from about two hours after dosing, so the earlier peak did not show as an earlier benefit; modafinil was ahead at 8 hours [9]. Caffeine’s action was shortest in Killgore 2008 [6]. Participants there guessed their treatment correctly in 57% of cases, so blinding was imperfect [9].

Side effects in these trials were few. Wesensten 2002 reported nausea and heart pounding [3]; Killgore 2008 reported more subjective side effects with caffeine than with modafinil [6]; the Dutch trial recorded no adverse events [9]. These were single doses in healthy people, so they say little about rare or delayed effects.

Regulatory status

Modafinil. In the US, FDA labelling covers wakefulness in adults with excessive sleepiness from narcolepsy, obstructive sleep apnea or shift work disorder; it is a Schedule IV controlled substance (label revised February 2025) [1]. In the EU, the European Commission decided on 27 January 2011, after a CHMP opinion of 18 November 2010, to restrict it to narcolepsy [2]. The UK and Germany were not rechecked for this article; see the modafinil guide.

Caffeine. The FDA describes it as an ingredient companies may add to foods, dietary supplements and over-the-counter medicines, with companies responsible for safety; it has no rule specific to energy drinks [18]. 21 CFR 182.1180 lists caffeine as generally recognized as safe in cola-type beverages [19]. A separate over-the-counter labelling rule allows the wording “Helps restore mental alertness or wakefulness when experiencing fatigue or drowsiness” [20]. In the EU, Regulation 1169/2011 (25 October 2011) requires “High caffeine content” labelling on beverages above 150 mg/l, excluding drinks named coffee or tea [21]. We did not check UK or German caffeine rules.

Risks and unknowns

Modafinil. In label trials of patients with sleep disorders, headache occurred in 34% versus 23% on placebo, nausea 11% versus 3%, anxiety 5% versus 1%, insomnia 5% versus 1%; 8% (74 of 934) stopped for an adverse reaction versus 3% [1]. The label warns of serious rash including Stevens-Johnson syndrome, psychiatric symptoms and cardiovascular events, and says modafinil produces “psychoactive and euphoric effects” in humans [1]. Details are in side effects and interactions.

Caffeine. The FDA lists increased heart rate, palpitations, high blood pressure, insomnia, anxiety, jitters, upset stomach, nausea and headache, and says concentrated pure products can be dangerous [18].

Not studied: long-term head-to-head use, women (three trials enrolled only men [11][12][13]), older adults, people with psychiatric or cardiac disease (some trials excluded psychiatric history [9][12]), and real-world work or driving. Sleep deprivation itself is the risk these trials target; Killgore’s team concluded the findings stress the importance of sufficient sleep [7].

The @dex7official tier list

On 20 October 2026, @dex7official posted “THE ONLY TRUE COGNITIVE ENHANCEMENT TIER LIST (NO COPES EDITION)” [22]. In the transcribed image, coffee sits in C and modafinil in D [23]. The post cites no study.

Verdict: partly supported. The direction fits the data. No trial found modafinil clearly stronger than caffeine for short-term alertness [3][5][6][9], and in rested men caffeine showed an effect where modafinil did not [12]. Two cautions. Later or longer-lasting effects favoured modafinil in one trial [9], and one 14-man study favoured it on a working-memory measure [11]. And “one tier” implies a measured gap that no trial supports; the list states no criteria, and the trial abstracts describe caffeine, not coffee. For why individual rankings disagree, see tier lists compared.

Why laboratory tests do not compare cleanly

• Doses and timing. Each trial picked its own doses, and peak times differ, so a test at one hour favours caffeine, and one at six may not.
• Who was tested. Young, healthy, screened volunteers, mostly military or lab-recruited; caffeine habits matter, and the trials handled them differently [9][12].
• Which test. Vigilance tasks measure staying awake; executive tasks and chess measure something else, and results diverge [7][13].
• Statistical significance. Small trials report significance, not whether a difference matters at work or behind a wheel.
• Sleep loss is the exception. Findings from sleep-deprived adults do not transfer to rested ones [16].

See also modafinil and sleep deprivation studies.

Frequently asked questions

Is modafinil stronger than caffeine?

In the sleep-deprivation trials above, they were about equally effective for the first hours. Differences were in how long effects lasted and in side effects, based on 10 to 16 people per group, or 32 in a crossover [3][5][6][9].

Do the trials show modafinil lasts longer?

Partly. The label and a Dutch trial of 32 aircrew point that way: modafinil outperformed caffeine on vigilance and sleepiness at 8 hours [1][9]. In an earlier trial caffeine’s action was the shortest [6].

Which has fewer side effects?

Trials reported few for either. One found more subjective side effects with caffeine [6], another none for either [9]. Modafinil’s label also lists rare serious reactions seen in patients [1].

Is caffeine regulated like modafinil?

No. In the US caffeine is a food ingredient under general rules, with an OTC alertness labelling rule; modafinil is a prescription Schedule IV drug [1][18][20].

Sources

1. Apotex Corp., “PROVIGIL (modafinil) tablets, prescribing information”, DailyMed (revised February 2025). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0391f182-1958-9fef-a944-53b229ce99e7
2. EMA, “Modafinil - referral” (CHMP opinion 18 Nov 2010; Commission decision 27 Jan 2011). https://www.ema.europa.eu/en/medicines/human/referrals/modafinil
3. Wesensten NJ et al., “Maintaining alertness and performance during sleep deprivation: modafinil versus caffeine”, Psychopharmacology 2002;159:238-47 (abstract). https://pubmed.ncbi.nlm.nih.gov/11862356/
4. Wesensten NJ et al., “Modafinil vs. caffeine: effects on fatigue during sleep deprivation”, Aviat Space Environ Med 2004;75:520-5 (abstract). https://pubmed.ncbi.nlm.nih.gov/15198278/
5. Wesensten NJ, Killgore WD, Balkin TJ, “Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation”, J Sleep Res 2005;14:255-66 (abstract). https://pubmed.ncbi.nlm.nih.gov/16120100/
6. Killgore WD et al., “Effects of dextroamphetamine, caffeine and modafinil on psychomotor vigilance test performance after 44 h of continuous wakefulness”, J Sleep Res 2008;17:309-21 (abstract). https://pubmed.ncbi.nlm.nih.gov/18522689/
7. Killgore WD et al., “Sustaining executive functions during sleep deprivation”, Sleep 2009;32:205-16 (full text, disclosure statement). https://pmc.ncbi.nlm.nih.gov/articles/PMC2635585/
8. Dagan Y, Doljansky JT, “Cognitive performance during sustained wakefulness: a low dose of caffeine is equally effective as modafinil in alleviating the nocturnal decline”, Chronobiol Int 2006;23:973-83 (abstract). https://pubmed.ncbi.nlm.nih.gov/17050212/
9. Wingelaar-Jagt YQ et al., “Effects of modafinil and caffeine on night-time vigilance of air force crewmembers: a randomized controlled trial”, J Psychopharmacol 2023;37:172-80 (full text). https://pmc.ncbi.nlm.nih.gov/articles/PMC9912306/
10. Zhong X et al., “Caffeine and modafinil modulate the effects of sleep deprivation on thalamic resting-state functional connectivity: a double-blind pilot study”, Sleep Med 2024;122:71-83 (abstract). https://pubmed.ncbi.nlm.nih.gov/39137663/
11. “Caffeine and modafinil counteract sleep deprivation through distinct neurocognitive pathways: an ERP study of object working memory”, Front Hum Neurosci 2026 (abstract via Europe PMC). https://pubmed.ncbi.nlm.nih.gov/42440885/
12. Repantis D et al., “Cognitive enhancement effects of stimulants: a randomized controlled trial testing methylphenidate, modafinil, and caffeine”, Psychopharmacology 2021;238:441-51 (full text). https://pmc.ncbi.nlm.nih.gov/articles/PMC7826302/
13. Franke AG et al., “Methylphenidate, modafinil, and caffeine for cognitive enhancement in chess”, Eur Neuropsychopharmacol 2017;27:248-60 (abstract). https://pubmed.ncbi.nlm.nih.gov/28119083/
14. McLellan TM, Caldwell JA, Lieberman HR, “A review of caffeine’s effects on cognitive, physical and occupational performance”, Neurosci Biobehav Rev 2016;71:294-312 (abstract). https://pubmed.ncbi.nlm.nih.gov/27612937/
15. Alzahrani AA et al., “Efficacy of fatigue countermeasures on cognitive performance and operational safety in military pilots: a systematic review”, Cureus 2025;17:e95823 (abstract). https://pubmed.ncbi.nlm.nih.gov/41328140/
16. Kredlow MA et al., “The efficacy of modafinil as a cognitive enhancer”, J Clin Psychopharmacol 2019;39:455-61 (abstract). https://pubmed.ncbi.nlm.nih.gov/31433334/
17. Roberts CA et al., “How effective are pharmaceuticals for cognitive enhancement in healthy adults?”, Eur Neuropsychopharmacol 2020;38:40-62 (abstract). https://pubmed.ncbi.nlm.nih.gov/32709551/
18. FDA, “Spilling the Beans: How Much Caffeine Is Too Much?” (content current as of 28 Aug 2024). https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much
19. US Government, “21 CFR 182.1180 Caffeine” (Cornell LII reproduction; accessed 2026-11-08). https://www.law.cornell.edu/cfr/text/21/182.1180
20. US Government, “21 CFR 340.50 Labeling of stimulant drug products” (Cornell LII reproduction; accessed 2026-11-08). https://www.law.cornell.edu/cfr/text/21/340.50
21. European Parliament and Council, Regulation (EU) No 1169/2011 of 25 October 2011, Annex III point 4.1 (as adopted; legislation.gov.uk copy, accessed 2026-11-08). https://www.legislation.gov.uk/eur/2011/1169/annex/III/adopted
22. @dex7official, “THE ONLY TRUE COGNITIVE ENHANCEMENT TIER LIST (NO COPES EDITION)” (20 Oct 2026). https://x.com/dex7official/status/2112691493261484516 (post text read through the fxtwitter mirror; the claim is the poster’s, not evidence)
23. @dex7official, tier-list post of 2026-10-20 (coffee in C, modafinil in D, placements read from the image on 2026-11-08). https://x.com/dex7official/status/2112691493261484516
24. Wingelaar-Jagt YQ et al., “Comparison of effects of modafinil and caffeine on fatigue-vulnerable and fatigue-resistant aircrew after a limited period of sleep deprivation”, Front Physiol 2023;14:1303758 (abstract). https://pubmed.ncbi.nlm.nih.gov/38260091/

This article is information, not medical advice.