The Study
Caffeine on the mind: EEG and cardiovascular signatures of cortical arousal revealed by wearable sensors and machine learning—a pilot study on a male group
This study showed that when people drank coffee, their brain waves and heart rate changed in a predictable way. But it didn't test if they felt more alert or did better on tasks—just that their body reacted. So we know coffee changes some signals, but we can't say for sure it makes you smarter or less tired.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When you drink a strong cup of coffee, your brain and heart react together: your heart slows down a bit, your brain stops 'zoning out' (less alpha waves), and starts working harder (more beta waves).
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 562 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — these changes mean your brain is more alert and less relaxed, even though your heart slowed down, which is surprising.
- 2This pattern could be used to detect alertness in real time using wearables.
- 3Heart rate dropped from 77 to 72 bpm.
- 4Alpha brain waves decreased by 1.8 dB.
- 5Beta brain waves increased by 2.4 dB.
- 6Machine learning could tell if someone had coffee or not with 79% accuracy.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Frontiers in Systems Neuroscience
Year
2025
Authors
Shabbir Chowdhury, Ahmed Munis Alanazi, Eyad Talal Attar
Related Content
Claims (6)
Consuming 162 mg of caffeine reduces heart rate, decreases alpha brain wave activity, and increases beta brain wave activity in healthy young men; a machine learning model using EEG data from seven scalp electrodes identifies this pattern with 79.2% accuracy.
High levels of caffeine maintain continuous activity in the body's fight-or-flight system and reduce activity in the rest-and-digest system.
Caffeine causes measurable changes in heart rate and brainwave patterns that wearable devices and machine learning can identify to monitor arousal levels in healthy young men.
A 162 mg dose of caffeine reduces heart rate, decreases alpha-band brain wave activity, and increases beta-band brain wave activity in healthy young men, indicating a measurable acute change in brain and heart function.
Caffeine consumption increases beta brainwave activity in the central scalp region due to true oscillatory changes, not general increases in background electrical noise, as measured by FOOOF decomposition in healthy young men.
A 162 mg dose of caffeine does not change systolic or diastolic blood pressure in healthy young men, but it does lower heart rate.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.