Does tryptophan help you sleep?

Only in one specific way. The meta-analysis finds it reduces the time spent awake after falling asleep, and finds no effect on the other sleep components. The effect appears from 1 g a day.

They are different points on the same pathway: tryptophan converts to 5-HTP and that into serotonin. That is why 5-HTP is sold at much lower doses. Quality evidence is scarce for both, and the Cochrane review analysed them together precisely because there were few good trials.

Does it work for depression?

The Cochrane review found 108 studies and only two, with 64 patients in total, were of sufficient quality. Although they did better than placebo, the conclusion is that the evidence is insufficient and, with antidepressants of proven efficacy and safety available, its clinical usefulness is limited. This is medical territory.

In the late eighties there was an outbreak of eosinophilia-myalgia syndrome associated with tryptophan products. The investigation linked it to a contaminant generated by one specific company’s manufacturing process, not to the amino acid itself. That is the reason to buy only with published batch testing.

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Tryptophan and 5-HTP · Weak evidence

What tryptophan and 5-HTP are for

The short answer. Tryptophan is the amino acid the body uses to make serotonin and then melatonin, which is where its two commercial uses come from: sleep and mood. For sleep there is a small meta-analysis that finds one specific thing, less time awake after falling asleep, and nothing else. For depression, the Cochrane review found that of 108 studies only two were of sufficient quality, and warns that proven alternatives exist. There is also a history worth knowing: an outbreak of eosinophilia-myalgia syndrome linked not to tryptophan itself but to how one company manufactured it.

Reviews find no consistent effect. It is listed because it sells, not because it works. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.

01 What it does and how much

Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.

Effects of tryptophan with their source
Effect	How much	Detail
Time awake after falling asleep	-81 min per gram	It is the only sleep component the meta-analysis finds affected. The direct comparison gives 56.55 minutes with under 1 g versus 28.91 minutes with 1 g or more. Four articles were analysed: the base is narrow. [1]
Other sleep components	no effect	The other sleep quality variables did not move. Selling tryptophan as something that makes you fall asleep sooner goes beyond the data. [1]
Dose at which it appears	1 g	The group with 1 g or more had less time awake than the group with under 1 g. Many products on the market fall short of that. [1]
Depression	insufficient evidence	Of 108 studies located, only two with 64 patients in total were of sufficient quality. They did better than placebo, but the review concludes the evidence is insufficient and clinical usefulness is limited given proven antidepressants exist. [2]
Safety history	OR 19.3	In the eosinophilia-myalgia syndrome outbreak, 97% of cases had consumed tryptophan from a single company versus 60% of controls. The problem was attributed to a contaminant from the manufacturing process, not to the amino acid. It is the strongest argument for demanding batch testing. [3]

02 How to take it

Dose. 1 g or more of tryptophan is what separates the sleep effect in the meta-analysis. 5-HTP is sold at much lower doses because it is one step further along the pathway.
When. At night, which is how it was tested for sleep.
How long before you notice it. Sleep trials measure the effect over nights, not weeks.

Details that change the result

Tryptophan and 5-HTP are not the same: 5-HTP is the intermediate metabolite towards serotonin and skips the rate-limiting step, which is why it is used in much smaller amounts.
With any serotonergic medication, antidepressants included, this is not something to take on your own: the risk of serotonin syndrome is a medical matter.
Melatonin has better evidence for sleep and a recognised condition of use under European regulation. If the goal is falling asleep, that is the better-supported route.
If there is one category where the batch testing seal justifies itself, it is this one: the historical outbreak came from a manufacturing contaminant.

03 When it makes sense and when it does not

Worth it if

Night-time awakenings, the only thing the meta-analysis finds affected, and from 1 g.
Bought with published batch testing, given the contamination history.

Not worth it if

To treat depression or anxiety, which are medical conditions and where the Cochrane review concludes the evidence is insufficient.
While taking antidepressants or other serotonergic medication without telling your doctor.
As a first choice for falling asleep, where melatonin has more support.

04 Sources

Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.

Sutanto CN, Loh WW, Kim JE. The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression. Nutr Rev. 2022;80(2):306-316. La suplementacion acorta el tiempo despierto tras el inicio del sueno (-81,03 min/g; DME -1,08); con 1 g o mas, 28,91 minutos frente a 56,55 con menos de 1 g; no afecta a los demas componentes del sueno. doi:10.1093/nutrit/nuab027
Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev. 2002;(1):CD003198. De 108 estudios localizados solo dos, con 64 pacientes, cumplieron los criterios de calidad; mejores que placebo (OR de Peto 4,10; IC 95 % 1,28-13,15) pero con evidencia de calidad insuficiente para ser concluyente. doi:10.1002/14651858.CD003198
Belongia EA et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J Med. 1990;323(6):357-365. El 97 % de los casos frente al 60 % de los controles habia consumido triptofano de una unica empresa (OR 19,3; IC 95 % 2,5-844,9); el brote se atribuyo a un componente quimico asociado a las condiciones de fabricacion. doi:10.1056/NEJM199008093230601

This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.

Questions about tryptophan

Answered with the data on this page

Does tryptophan help you sleep?: Only in one specific way. The meta-analysis finds it reduces the time spent awake after falling asleep, and finds no effect on the other sleep components. The effect appears from 1 g a day.
Tryptophan or 5-HTP?: They are different points on the same pathway: tryptophan converts to 5-HTP and that into serotonin. That is why 5-HTP is sold at much lower doses. Quality evidence is scarce for both, and the Cochrane review analysed them together precisely because there were few good trials.
Does it work for depression?: The Cochrane review found 108 studies and only two, with 64 patients in total, were of sufficient quality. Although they did better than placebo, the conclusion is that the evidence is insufficient and, with antidepressants of proven efficacy and safety available, its clinical usefulness is limited. This is medical territory.
Is tryptophan safe?: In the late eighties there was an outbreak of eosinophilia-myalgia syndrome associated with tryptophan products. The investigation linked it to a contaminant generated by one specific company’s manufacturing process, not to the amino acid itself. That is the reason to buy only with published batch testing.

And now, which to buy

Prices, kept apart from the evidence

This page explains what tryptophan does and deliberately names no brand. The comparison is the other half: 30 products from 4 stores from €0.058 per capsule, sorted by price and by how verifiable their certification is.

See the tryptophan and 5-htp comparison

Other guides

What each supplement does, with its sources