The people it speaks toFieldwork 2024
30.5% of US adults
slept less than 7 hours on average in a 24-hour period in 2024, in the National Health Interview Survey.
CDC National Center for Health Statistics, 2026NOW L-Tryptophan 500mg
NOW L-Tryptophan 500mg.
Backed by human trials
L-Tryptophan is the lead active here, studied most for winding down in the evening. 6 human studies on L-Tryptophan back this formula, each one cited. Who it fits: for everyone, adults.
Clinically dosedFull label disclosure
1Active ingredient6Human studies1000 mgL-Tryptophan
Verified by IngredientMDHow we read this product
- 01We read the label.
The panel on the left is the one we evaluated, line by line.
- 02Every active, separately.
All 1 actives checked against the clinical evidence: dose, form, and what the research actually shows.
- 03Then the formula as a whole.
Doses, ratios, and how the ingredients work together. That assessment is the verdict above: "Backed by human trials".
- 04Earned, not bought.
The verdict is public and identical whether or not a brand pays. A formula that does not clear the bar gets nothing.
Read by the engine against 2.1 million data points from clinical trials, PubMed and more than a hundred vetted sources. No individual reviewer is named or implied.
The receipts
6
Human studies
1000 mg
L-Tryptophan
1 g per serving sits inside the studied 250 mg-1 g range
L-Tryptophan, Silber & Schmitt 2010 J Psychiatry Neurosci meta-analysis; Hartmann 1982 sleep research
Cross-checked against 207 documented interactions for these actives.
Read the evidenceL-Tryptophan, the evidence →
Inside the formula
In context
The gap this formula speaks to.
Public health figures the engine matched to this formula's ingredients. Reported by their source, cited and dated, never written by the brand.
The people it speaks toFieldwork 2024
54.8% of US adults
woke up feeling well-rested every day or most days in the past 30 days in 2024, in the National Health Interview Survey.
CDC National Center for Health Statistics, 2026The people it speaks toFieldwork December 2023
63% of US adults who want more sleep
say they frequently experience stress, against 31% of those who get the sleep they need, in a December 2023 Gallup poll.
Gallup, 2024The people it speaks toFieldwork May 2024
74% of US adults
report their sleep is sometimes, often or always disrupted by stress, in a 2024 survey commissioned by the American Academy of Sleep Medicine.
American Academy of Sleep Medicine, 2024The people it speaks toPublished 2022
2.1% of US adults
reported using melatonin in 2017 to 2018, up from 0.4% in 1999 to 2000, across ten cycles of the National Health and Nutrition Examination Survey.
JAMA, 2022The people it speaks toFieldwork 2024
15.4% of US adults
had trouble falling asleep, and 18.1% trouble staying asleep, every day or most days in the past 30 days in 2024, in the National Health Interview Survey.
CDC National Center for Health Statistics, 20268 more
12.9% of US adults
used a sleep aid most days or every day in the past 30 days to help them fall or stay asleep in 2024, in the National Health Interview Survey.
CDC National Center for Health Statistics, 202642% of US adults
say they get as much sleep as they need, the first time since Gallup began asking in 2001 that fewer than half did, in a December 2023 poll.
Gallup, 202459 to 66 days
was the median time it took adults to make a new daily health habit automatic across the studies a 2024 review pooled, with individuals ranging from 4 to 335 days.
Systematic review and meta-analysis, 202461% to 74%
About 61 to 74 percent of adults refilling a long-term medicine on their own stopped within a year, versus 33 to 44 percent on one set pickup day.
Cohort study, 2015Systematic review and meta-analysis, 2022
Across combined trials, tryptophan shortened time spent awake after falling asleep by about 81 minutes per gram taken, with the strongest effect at 1 gram or more.
Nutrition ReviewsSutanto et al., 2022 (Nutrition Reviews)PMID 33942088
Systematic review, 2020
Across 11 randomized trials in healthy adults, taking 0.14 to 3 grams of tryptophan a day alongside usual meals was associated with lower negative mood and higher positive mood.
Journal of Dietary SupplementsMeta-analysis, 2025
Across combined trials, tryptophan was among supplements linked to better self-reported sleep quality scores, with the size of the effect varying widely between studies.
NutrientsMei et al., 2025 (Nutrients)PMID 41470897
Randomised trial, 2025
A folic acid and creatine trial also mapped blood chemical patterns, including tryptophan-related compounds, but these are only marker-level links found within a study of other nutrients.
Environmental Science and TechnologyPopulation figures from public health data. Context for the category, not a statement about any individual and not a claim about this product.
Every one of these is a fact the engine could ground.
Each line below was derived from this formula's own record at the time of verification. Nothing here was written by the brand, and nothing can be added that the evidence does not carry.
- Studied in people6 human studies on L-Tryptophan back this formula, each one cited.
- A mechanism that is settledHow L-Tryptophan works is settled pharmacology.
- Why this formatIt is a capsule, so the amount per serving is fixed and travels without measuring.
- The exact form, describedThe form on the label is L-Tryptophan (free form). The record says what that form is and what it suits.
- Full label disclosureEvery ingredient on this label carries its own declared amount.
- Where it comes from and how it is madeL-Tryptophan is made by fermentation.
- Positions this formula already qualifies forThis formula already qualifies for positions beyond the one it is sold into, on the evidence it carries.
- A position nobody is holding yetSome of those positions are ones almost nobody is selling to yet.
How each ingredient usually behaves over time.
One ingredient, from its own page.
- L-TryptophanAbout one to two hours
Blood levels peak in one to two hours, so an evening dose acts the same night. Steadier mood across a week takes one to two weeks of nightly use.
How each ingredient usually behaves over time, from its own page on IngredientMD. General timing for the ingredient, not a measurement of this product.
Capsule
It is a capsule, so the amount per serving is fixed and travels without measuring.
Best forMost standard doses, and anywhere a short, clean label is the point.
Questions shoppers ask
- Is NOW L-Tryptophan 500mg independently verified?
- Yes. IngredientMD reviewed this formula independently and verified it in Oct 2026. The verdict is earned, not bought: brands can't edit or purchase it.
- What's in NOW L-Tryptophan 500mg?
- NOW L-Tryptophan 500mg is built on L-Tryptophan. Each ingredient links to its own evidence page on IngredientMD.
- Were ingredient interactions checked?
- Yes. The combination was screened against 207 documented interactions for these actives in IngredientMD's interaction database.
- Who is IngredientMD?
- IngredientMD is an independent supplement-science platform. We analyze ingredients and formulas against clinical research, and we verify products only when they clear our bar. Labs run the tests. We review the results.
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These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This record is not medical advice. Always consult your healthcare provider before starting any supplement regimen.
Independent review by IngredientMD, not commissioned by NOW FoodsWork at NOW Foods? This verification is yours to claim →