Per user reports and the small body of subjective-rating data:

• Onset: 30-60 min after dose on empty stomach. Some report a mild "warmth" or relaxation by 45-60 min.
• Peak: ~60-120 min post-dose. Most pronounced effect: gentle drowsiness, not knockout. Body relaxes. Not the "GABAergic mush" feel of phenibut/Z-drugs — much cleaner.
• Sleep: Falling asleep is easier; many report fewer middle-of-night awakenings.
• Dreams: Vivid dreams in maybe 30-40% of users, especially early in protocol. Some find this fascinating, some find it annoying. Often fades with continued use.
• Morning: No grogginess at 1 g doses. This is one of tryptophan's best features vs antihistamines (diphenhydramine) or Z-drugs.
• Mood: Subtle mood lift over 1-2 weeks of consistent dosing in some users; not a serotonergic "rush" — more a baseline smoothing.

Variability: 5-HTTLPR S/S carriers respond more strongly (van Dalfsen 2019). High-inflammation states (CRP elevated, sleep-deprived, sick, overtraining) likely blunt response via the kynurenine shunt. Low B6 / low Mg / low Fe also blunt response (TPH cofactor deficiency).

• Tolerance buildup: Minimal/none at supplement doses. Tryptophan is restoring substrate, not pushing receptors. No reported pharmacological tolerance.
• Recommended cycle: Daily, indefinitely. No cycle needed. This is one of tryptophan's strongest features for daily-driver sleep stack.
• Reset protocol: N/A — no tolerance to reset. If subjective effect dims, suspect (1) increased inflammation/IDO activity, (2) cofactor depletion (B6, Mg, Fe), or (3) the placebo phase wearing off.

Synergistic with

• magnesium-glycinate — already in V4 at 400 mg elemental. Mg is a TPH cofactor and a calming GABAergic adjunct. Strong pairing.
• vitamin-b6 (P5P) — direct AAAD cofactor (5-HTP → serotonin step). Add 25-50 mg P5P with tryptophan if response suboptimal. Not currently in V4.
• melatonin (low-dose, 0.3-0.5 mg phase-shift dose) — feeds different points of the same pathway; tryptophan = substrate, melatonin = downstream phase-shift signal. Stacks cleanly.
• l-theanine (200 mg, already in V4) — different mechanism (GABA/glutamate) but additive on subjective relaxation. Fine to co-administer pre-bed.
• glycine (technically) — see "Replaces" below. Glycine has a real but small effect (lowers core body temp, NMDA modulation) that doesn't conflict with tryptophan. Could co-administer, but the V5 plan correctly drops it because it adds cost/pill burden for marginal effect, and the evidence base for glycine sleep is weaker (mostly Ajinomoto-funded small trials).
• carbohydrate (small, ~15-20 g) — insulin-mediated LNAA shunt. Strongest evidence-backed timing trick.
• agomelatine (Rx melatonin agonist + 5-HT2C antagonist) — would stack mechanistically but a user in this archetype is not on it; flagged for completeness.

Replaces

• glycine (V4: 3 g pre-bed) — explicit V5 swap. Glycine: F-grade evidence per the user's prior research (small Ajinomoto-funded trials, no independent replication, mechanism for sleep is plausible-but-thin). Tryptophan: A-tier evidence + mechanistically more relevant for melatonin pathway in a late-chronotype trying to phase-advance. Tryptophan wins on both evidence and mechanism for users matching this archetype's use case. Both could be co-administered (no antagonism), but pill burden/cost optimization argues for one or the other.

Avoid stacking with

• 5-htp — redundant; adds 5-HTP without the regulatory benefit of tryptophan's TPH gating. Pick one. Tryptophan is preferred for the regulatory/quality-control reason discussed in Mechanism.
• High-protein meals or protein shakes within 2 hours of dose — LNAA competition kills brain delivery. Time the dose accordingly. (Bedtime dose is naturally far from training-day protein.)
• MAOIs (selegiline at low MAO-B selective doses likely fine, but selegiline ≥10 mg/day loses selectivity; phenelzine/tranylcypromine are real risk). the user's V stack includes optional selegiline 1-2.5 mg/day — at this dose, selectivity for MAO-B is preserved and serotonin syndrome risk with tryptophan is low. Above 5 mg/day selegiline, treat as MAOI and reduce or skip tryptophan.
• Tramadol, triptans, dextromethorphan in cough syrups — modest serotonergic load. Not fatal at supplement tryptophan doses but worth pausing tryptophan during a tramadol course.

Neutral / safe co-administration

• All other V4 stack items (DHA, magtein, citicoline, NAC, PS, curcumin, rhodiola, theanine, D3+K2, beta-alanine, vitamin C).
• Modafinil (V5 plan) — different mechanism, AM dosing, no overlap with PM tryptophan. Safe.
• Bromantane, Adamax/Semax, ALCAR — all AM, no overlap.
• Creatine — no interaction.

CYP enzymes: Tryptophan is not a CYP substrate or inhibitor in any clinically relevant way. No CYP-mediated interactions.

Contraceptives: No interaction.

Variants a user in this archetype should check from 23andMe (June 2026):

• 5-HTTLPR (SLC6A4 promoter variant) — short (S) allele carriers have reduced serotonin transporter expression → higher baseline extracellular 5-HT but lower 5-HT system efficiency. S-allele carriers respond more strongly to tryptophan supplementation (van Dalfsen 2019). 23andMe doesn't directly genotype 5-HTTLPR (it's an indel, not a SNP), but related SNPs (rs25531, rs4795541) give partial info. Promethease/SelfDecode interpret raw data more thoroughly.
• TPH2 SNPs (rs4570625 G-703T promoter; rs4290270; rs7305115) — affect brain serotonin synthesis rate. Some variants associated with depression/suicidality risk. T carriers of rs4570625 may have lower TPH2 activity → more substrate-limited → potentially better tryptophan response (untested directly).
• TPH1 SNPs (A218C, A779C) — peripheral pineal/gut TPH. Less neuropsychiatrically relevant; more relevant to peripheral 5-HT (gut, platelet).
• MAO-A VNTR (low-activity vs high-activity allele) — high-activity = faster serotonin breakdown. Low-activity = slower, possibly lower tryptophan need. Famous "warrior gene" variant — a user in this archetype should check this for general behavioral/aggression context, not just tryptophan dosing.
• IDO1 / TDO2 SNPs — affect kynurenine flux. Not commonly reported by 23andMe; needs raw-data analysis.
• MTHFR (C677T, A1298C) — affects methylation, indirectly affects BH4 (TPH cofactor). C677T homozygous T/T = reduced BH4 regeneration → potentially blunted serotonin synthesis. Very common variant. If positive, methylfolate (5-MTHF) and methyl-B12 supplementation may help.

Practical action after 23andMe results land (~June 5-15): If S/S 5-HTTLPR or T/T MTHFR or low-activity MAO-A → tryptophan response should be above average. If L/L 5-HTTLPR → response may be subtle; trial period is informative.

Recommended for users in this archetype: NOW Foods L-Tryptophan 500 mg, 2 caps pre-bed, via iHerb. Reasons: (1) already in the user's iHerb cart workflow, (2) NOW publishes CoAs and uses TryptoPure, (3) ~$13-15/mo fits the V4 budget.

V5 swap math: Drop NOW Foods Glycine 3 caps/day ($8-10/mo) → add NOW Foods Tryptophan 2 caps/day ($13-15/mo). Net: +$3-5/mo to V4 monthly cost. Negligible.

Baseline (before starting)

• Plasma tryptophan + kynurenine:tryptophan ratio if available (specialty panels — not standard CMP).
• hs-CRP — inflammation marker; predicts kynurenine-shunt magnitude.
• B6 (PLP), RBC magnesium, ferritin — TPH/AAAD cofactors.
• 25(OH)D — the user already tracking.
• Subjective sleep diary baseline — sleep onset latency, WASO, total sleep time, morning grogginess (1-10 scale) for 7-14 days pre-trial. Most actionable for users in this archetype since labs come in June.

During use

• Sleep diary metrics weekly for first month, monthly after.
• Subjective mood (1-10) weekly.
• If response disappointing at 4 weeks: re-check hs-CRP, B6, Mg, ferritin.

Post-cycle (if ever cycled)

• N/A — daily-safe, no cycling needed.