Public-ready7/5/2026

L-Theanine

Papers analyzed

Cognition, memory, and focusStress Response and Sleep Changes

What to look for in this research

Cognition, memory, and focus is the main area connected here, and any felt benefit should be read together with the human evidence base.

Main benefit evidence

Review human evidence by goal.

Cognition and focus

Cognition, memory, and focus

Measured outcomes: Cognition, memory, and focus

Potential benefit studied in Cognition and focus.

Goal tierB

Direct human evidence

Some accumulation4 direct studies

Positive

No clear difference

Mixed

Negative

Positive study ratio75%

The share of automatically classified direct studies with a positive result. It is not a personal probability or a certainty assessment.

Research intake observed

One study used 200 mg/day.

Dose confirmed in 1 of 4 direct studies.

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200 mg/day

rct

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Sleep

Stress Response and Sleep Changes

Measured outcomes: Sleep quality

These findings come from stress response, cortisol, anxiety, or sleep outcomes. They may mix felt benefits with physiological markers.

Goal tierNot rated yet

No direct evidence for general supplement use is confirmed under the current standard.

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What does a research result actually tell you?

Reading research

Improvement after a supplement is not the same as a comparative result

Start with the comparison. A before-and-after change alone cannot isolate the contribution of an ingredient.

No significant difference and an unreadable result mean different things

A reported null comparison contains a result. An abstract without an interpretable comparison leaves a question unresolved.

Ten papers do not necessarily mean ten independent studies

Count original research separately from research that reanalyzes it. Publication volume is neither replication nor a quality rating.

Side effects and combination findings in studies

Findings from studies of this ingredient alone are separated from findings involving another supplement or medication.

Caution signals

Side effects + combos + curated rules

Key precautions

No combination caution signal is clear enough to show right now. This does not guarantee safety.

1 combo signals and 0 added-signal combos shown below.

These are signals reported in studies. They do not predict what will happen to an individual.

Positive combinations studied

Positive combination findings are separated by how the study compared the groups. This is not a recommendation to combine them.

Positive findings when used together

The combination had a positive result, but the contribution of each ingredient could not be separated.

CaffeineL-theanine combined with caffeine significantly reduced caffeine-induced tachycardia (17% vs 92%) and state anxiety compared to caffeine alone.

L-Theanine

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