That's why I usually pay most attention to meta-analyses, if the studies aren't huge and preregistered: https://pubmed.ncbi.nlm.nih.gov/24946991/ https://pubme

That's why I usually pay most attention to meta-analyses, if the studies aren't huge and preregistered: https://pubmed.ncbi.nlm.nih.gov/24946991/ https://pubmed.ncbi.nlm.nih.gov/24946991/ That meta-analysis kinda suggests theanine doesn't really have much effect; caffeine improves attention.