Compound or practice · Supplement
L-Tyrosine
A catecholamine precursor that buffers performance under acute stress and sleep loss — and does little on a normal day.
- Overall grade
- Grade C
- Last revised
- 2
- graded outcomes
- 0
- references listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
1 at grade C · 1 at grade D — 2 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Cognition under acute stress / sleep lossEvidence grade C
Condition-specific
Moderatemixed
- Cognition when restedEvidence grade D
No benefit
Trivialhigh
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: Cognition under acute stress / sleep loss (grade C); Cognition when rested (grade D).
- Caution with Levothyroxine: Tyrosine is a thyroid-hormone precursor — coordinate if on thyroid meds.
Interactions
Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.
LevothyroxineCaution
Tyrosine is a thyroid-hormone precursor — coordinate if on thyroid meds.
CaffeineWorks together
Under sleep deprivation the stack beats either alone.
The evidence in words
What it is
L-tyrosine is the amino-acid precursor to dopamine, norepinephrine, and epinephrine. The idea is to supply raw material when stress depletes these neurotransmitters faster than the brain can rebuild them.
How it works
Under acute stressors — cold, noise, sleep deprivation, cognitive load — catecholamine turnover spikes and tyrosine availability can become limiting. Supplementing may sustain synthesis and protect performance in exactly those conditions.
What the evidence shows
The evidence is genuinely condition-dependent: tyrosine helps preserve working memory and cognitive flexibility under acute stress or sleep loss, but shows little benefit in rested, unstressed people. It is not a general nootropic; it is a stress buffer.
How to use it
500–2,000 mg taken ~30–60 minutes before an acute stressor or demanding, sleep-deprived session. Not useful as a daily baseline.
Safety & interactions
Well tolerated. Theoretical caution with MAOI antidepressants and thyroid medication; those on such drugs should check first. Caffeine — Under sleep deprivation the stack beats either alone. levothyroxine — Tyrosine is a thyroid-hormone precursor — coordinate if on thyroid meds.
Bottom line
Situational, not daily. Take it before a cold, sleepless, or high-pressure cognitive challenge; skip it on ordinary days where it does nothing.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Situational
- 500–2,000 mg, 30–60 min pre-stressor.
Goes with
- CaffeineUnder sleep deprivation the stack beats either alone.Evidence grade A
Related reading
Entries that share this one's tags or conditions.
- L-Tyrosine for Cognition under acute stress / sleep lossEvidence grade C — Condition-specificEvidence grade C
- L-Tyrosine for Cognition when restedEvidence grade D — No benefitEvidence grade D
- L-Tyrosine: dosage and how to take it500–2,000 mg, 30–60 min pre-stressor.Evidence grade C
- L-Tyrosine: side effects, safety & interactionsWell tolerated. Theoretical caution with MAOI antidepressants and thyroid medication; those on such drugs should check fEvidence grade C
Sources
This entry lists no references of its own.
Last revised . A grade is this entry's reading of the evidence, not medical advice.