L-tryptophan for Sleep

No doubt you have felt the intense drowsiness of post-Thanksgiving dinner. And like us you might be wondering how much of that drowsiness is due to the turkey and how much of it is it just your body focusing on the giant meal you just ate.

Let’s take a look at L-tryptophan, specifically, what it is and how this amino acid naturally produced by your body works.

We’ll also explore how and when to take L-tryptophan to address sleep difficulties and answer the question: Does it actually work and help you get better sleep?

What is L-tryptophan?

L-tryptophan is an essential amino acid, which means your body does not produce it naturally and requires it from outside sources. 

Technically, you can get all of the L-tryptophan your body needs through a healthy diet. But you can also supplement L-tryptophan, especially if you are having sleep issues or mental health problems.

L-tryptophan has been shown to help those struggling with bipolar disorder, obsessive compulsive disorder, and depression. The results of these case studies aren’t definite, but they show promise that L-tryptophan supplements can provide some relief. 

Adding additional L-tryptophan to your diet is thought to improve your sleep process, which is the focus of this article. 

Why is L-tryptophan used for sleep?

L-tryptophan, often referred to as just tryptophan, has sleep-promoting effects because it is a necessary chemical in the biosynthesis pathway for serotonin, an important compound for sleep. 

L-tryptophan is converted to 5-HTP, or 5-hydroxytryptophan, which is the immediate precursor to serotonin, one of the major “happy chemicals” that goes by the lesser-known name of 5-hydroxytryptamine.

Serotonin is a chemical that plays an important role in regulating mood, appetite, sleep, and behavior.  It’s found in the gut, brain, and blood platelets. The nervous system uses serotonin to communicate messages between brain cells, so it’s a neurotransmitter.

It used to be thought that serotonin was mainly responsible for wakefulness, but recent research suggests it plays an important role in contributing to sleep pressure, or the feeling of sleepiness that builds up throughout the day. Additionally, serotonin is converted to melatonin in the pineal gland. Melatonin is an important hormone that regulates our sleep-wake cycles by making us feel sleepy.

While you can take tryptophan and melatonin supplements, you can’t find serotonin supplements. You also can’t find foods that have serotonin in them. You must rely on increasing your tryptophan or 5-HTP levels in the body to increase your serotonin levels. L-tryptophan is increased either through eating tryptophan-rich foods or supplementation, while 5-HTP levels are increased through supplementation. 

Tryptophan-rich foods that may boost serotonin levels

Instead of taking a tryptophan supplement, some people try to increase the tryptophan in their bodies through their diet. There are foods that are known to have a higher amount of tryptophan. So, if you’re looking to increase tryptophan through your diet, you could eat: 

  • Nuts and seeds: Squash, pumpkin, chia, and sesame seeds
  • Soy foods: Soybeans, tofu and tempeh
  • Cheese: Parmesan, cheddar, and mozzarella 
  • Meat: Lamb, pork, rabbit, and lean roast beef
  • Poultry: Chicken and turkey
  • Fish: Tuna, halibut, salmon, and trout
  • Shellfish: Crab, lobster, octopus, clam, and prawns
  • Uncooked Oats: Oats, buckwheat, and oat cereal
  • Beans and Lentils: White, cranberry, yellow, and pinto beans
  • Eggs: The entire egg

There is some evidence that eating pure carbohydrates alongside these foods can help boost serotonin levels even further. When you eat carbohydrates, this helps the body preferentially shuttle tryptophan to the brain in order to create serotonin.

Supplementing L-tryptophan: How it’s done and why

Dietary supplements of L-tryptophan is sometimes taken to address a nutrient deficiency, but more commonly its used as a sleep aid or to improve other health conditions. For example, women can take tryptophan to help improve symptoms such as mood swings caused by premenstrual syndrome.

A healthy diet will provide all of the tryptophan you need in your body to address the recommended daily intake. However, those suffering from poor sleep quality will often add tryptophan to their diets in significantly higher quantities, anywhere from 500mg to six or more grams, to improve their quality of sleep. Let’s explore what the research says about how L-tryptophan supplements interacts with sleep.

L-tryptophan for sleep: What the research is saying

Studies on the effects of tryptophan supplementation for sleep problems date back to the early 1970’s. The studies conducted use dosage ranges that vary from as little as 250mg to as high as 15g. 

There is a wealth of scientific evidence that L-tryptophan reduces sleep onset latency, or the time it takes to fall asleep. In one review of six studies evaluating the effects of L-tryptophan on sleep latency, all but one study noted an average decrease in sleep onset time across all participants, with reductions ranging from eight minutes to 13 minutes. The effects were not found to be dose dependent, but a minimum dose of one gram was the most effective, taken 20 minutes before bedtime.[1

The same meta-analysis reviews six other studies assessing L-tryptophan use for sleep disorders, specifically, symptoms of insomnia. All six studies, totaling 63 patients with insomnia, demonstrated improvements in several sleep parameters, especially total sleep time and the amount of intermittent awakenings during the night. 

In most studies, the mean total sleep time was increased by more than one hour in the tryptophan-taking group. In these studies, the researchers conclude that L-tryptophan shows the highest efficacy in improving sleep when repeatedly taken at a low dose (less than three grams) with intervals of no L-tryptophan every few days, which they dub “interval therapy”.[1

Potential side effects and risks of L-tryptophan supplementation

Tryptophan supplements are generally well tolerated, but some adverse effects reported include daytime drowsiness, dizziness, and dry mouth. At higher doses, the side effects of L-tryptophan may include nausea, stomach pains, lack of appetite, and headaches. Due to its sedative properties, supplementing tryptophan alongside strong sedatives such as alcohol or benzodiazepines isn’t advised. 

If you have a history of liver disease, kidney disease, cardiac problems, or diabetes, be sure to speak with a healthcare professional before tryptophan supplementation. One of tryptophan’s metabolites is xanthurenic acid, which in high concentrations is correlated with insulin resistance. 

Caution should also be taken if you are taking antidepressant drugs such as SSRIs that increase serotonin. Too much serotonin can lead to serotonin syndrome, a potentially serious disorder characterized by shivering, loss of muscle coordination, agitation, and muscle rigidity.

Lastly, L-tryptophan supplementation was found to not affect tryptophan levels in breast milk according to one recent study, so it may be safe for those breastfeeding. However, further studies will have to validate this conclusion.

Why we use L-tryptophan

We use L-tryptophan because of its long history of being safe and clinically effective for a variety of sleep issues, as well as its versatility in helping modulate many aspects of one’s wellness. As previously noted, it is a precursor to serotonin, an integral hormone for sleep and relaxation. 

Remrise uses a synergistic combination of L-tryptophan along with L-theanine, passionflower and hops in order to address all aspects of one’s sleep. 


  1. Schneider-Helmert D, Spinweber CL. . Evaluation of L-tryptophan for treatment of insomnia: a review . Psychopharmacology (Berlin) 1986; 89:1–7.

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