Also known as: theanine, suntheanine
Latest evidence update: 2025-12-01
Strongest in Replication (78). Held back by Recency (29).
Solid mix of RCTs with some methodological gaps.
Confirmed across many independent studies with significant findings.
Thousands of participants across the literature.
Mostly aligned, with some divergence.
Mostly pre-2020 research; updates may be needed.
Improves sleep quality and duration when combined with walnut peptide
Enhances focus and reaction time when combined with caffeine in sleep-deprived individuals
May help balance the stimulating effects of caffeine to promote a calm yet focused state
Has minimal impact on next-morning physical performance, cognitive function, or balance
Recommended: 100-200mg
ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.
May improve attention and mental processing speed in sleep-deprived conditions when combined with caffeine