L-Tryptophan
The full upstream precursor to serotonin and melatonin. Gentler than 5-HTP — the body converts as needed rather than flooding the system.
Moderate evidence for sleep onset, mild depression / mood stabilisation, and PMS-related mood symptoms. Most clinical research from the 1970s–1980s (when L-tryptophan was Rx); modern RCTs are fewer. Effects: within nights for sleep; 2–6 weeks for mood.
L-Tryptophan is an essential amino acid the body uses to build serotonin (mood, calm, satiety) and melatonin (sleep). Unlike 5-HTP, which skips a regulatory step, tryptophan goes through the full conversion pathway, allowing the body to titrate based on need. Less aggressive at raising serotonin acutely, but typically gentler on the gut and less likely to cause the serotonin-syndrome-adjacent issues that 5-HTP can. Brain uptake is the rate-limiting step — it competes with other amino acids for transport, which is why tryptophan works best on an empty stomach or with a small carb that triggers an insulin response (insulin pulls other amino acids into muscle, clearing the runway for tryptophan).
- Form
- L-Tryptophan capsules or powder. Quality has historically been a concern (1989 EMS / Showa Denko incident) — buy pharmaceutical-grade from reputable brands.
- Dose
- 500–2,000 mg/day. 1,000–2,000 mg pre-bed for sleep. Higher doses (3 g+) used clinically for refractory depression.
- Timing
- Empty stomach pre-bed for sleep, or with a small carbohydrate (like a piece of fruit) to assist brain uptake. Not with high-protein meals.
- Schedule
- Daily for sustained use, or as-needed.
- Side effects
- Generally well-tolerated. Drowsiness (the point, at PM dose). Mild nausea, headache, dry mouth. Vivid dreams.
- Interactions
- SSRIs, SNRIs, MAOIs, tramadol — theoretical serotonin syndrome risk. Sedatives, benzodiazepines — additive drowsiness. Carbidopa (Parkinson's) — interaction reported.
- Contraindications
- On serotonergic medications without provider input. Eosinophilia-myalgia syndrome history (the contaminant scare). Carcinoid syndrome (already-elevated serotonin).
- Lab markers
- Not standard. Subjective sleep and mood tracking.
- Food sources
- Turkey (the famous one — but the post-Thanksgiving sleepiness is mostly about the carbs, not the tryptophan), chicken, eggs, cheese, fish (especially tuna), tofu, pumpkin seeds, oats, milk.
Pairs with
Vitamin B6 (P5P) — required cofactor for serotonin synthesis. Magnesium glycinate, glycine (sleep stack). Carbohydrate (timing trick for brain uptake).
within Amino acids & derivatives