The Study
Multi-ingredient energy dietary supplement with a small amount of caffeine modulates central and autonomic nervous system after a single use.
This study saw that after people drank an energy drink, their heart and brain showed some changes. But we don’t know if the drink caused those changes or if something else did. So we can only say they happened together, not that one made the other happen.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave people a drink with just 55 mg of caffeine — less than a cup of coffee — and watched how their brain and heart responded.
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 535 / 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 — even a small amount of caffeine can affect both brain and heart signals in adults, especially if they're feeling tired.
- 2The drink changed heart rhythm patterns (PRQ and QTc intervals) and brain wave patterns linked to fatigue.
- 3Heart rate variability (LF power) changed at the same time as brain waves.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Neuroscience
Year
2025
Authors
Karina Maciejewska, Klaudia Duch, M. Giza, Aleksandra Nas
Related Content
Claims (4)
High levels of caffeine maintain continuous activity in the body's fight-or-flight system and reduce activity in the rest-and-digest system.
A single dose of a caffeine-containing energy supplement alters electrical activity in the heart and brain in adults, as measured by ECG and EEG.
A single dose of an energy supplement with 55 mg of caffeine alters brainwave patterns during rest in a way that counteracts changes typically seen during mental fatigue in adults.
In adults, changes in heart rate variability at low frequencies are associated with changes in brainwave patterns during rest after consuming a low-dose caffeine energy supplement.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.