Understanding Tryptophan


Written by Dr. Michael Breus

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Medical Disclaimer: The following content should not be used as medical advice or as a recommendation for any specific supplement or medication. It is important to consult your healthcare provider prior to starting a new medication or altering your current dosage.

Table of Contents

Tryptophan is an essential amino acid that plays an important role in a handful of different bodily processes. Many people associate tryptophan with turkey and feelings of sleepiness after holiday meals, but it is found in a wide variety of foods and beverages. Some people also take tryptophan supplements, though their safety and efficacy is not well-researched.

There are common misconceptions about what tryptophan is, how it works, and whether or not it makes you sleepy. We delve into the science behind tryptophan and discuss why it is important to your overall health.

Key Takeaways


  • Tryptophan is an amino acid that contributes to relaxation and healthy sleep patterns.
  • Tryptophan is a precursor to serotonin, which affects mood and sleep.
  • Tryptophan-rich foods include meat, fish, dairy products, nuts, and some fruits.
  • A balanced diet is essential for optimal sleep quality, so speak to your doctor before taking tryptophan supplements.

Why Is Tryptophan Important?

Tryptophan is integral to infant growth and development, as well as the production and upkeep of various enzymes, muscles, neurotransmitters, and proteins in the body. With the help of iron, riboflavin, and vitamin B6, the liver converts tryptophan into vitamin B3, also known as niacin. Niacin plays a role in metabolizing energy and creating DNA.

Tryptophan is also needed to produce serotonin, a neurotransmitter involved in sleep, appetite, pain, and mood. Serotonin then works with enzymes to create melatonin, a hormone that regulates your sleep-wake cycle by making you feel tired at bedtime. This progression that begins with tryptophan consumption and ends with melatonin production is crucial for healthy sleep.

There are two types of tryptophan, L-tryptophan and D-tryptophan. Both serve the same general functions but differ slightly at the molecular level. Like other essential amino acids, tryptophan must be consumed as part of your diet as your body cannot produce it on its own.

Which Foods Contain Tryptophan?

Tryptophan is found in many foods and beverages, a large number of which are also rich in protein. These include:

  • Turkey and chicken
  • Whole and 2% milk
  • Wheat and white bread
  • Semisweet and sweet chocolate
  • Canned tuna
  • Cheddar cheese
  • Peanuts
  • Oats
  • Bananas
  • Apples
  • Prunes

Does Turkey Make You Sleepy?

A common belief is that tryptophan is responsible for the feelings of drowsiness many people feel after consuming turkey during holiday meals. This is only partially true. While tryptophan is tied to sleep, turkey contains less tryptophan than other holiday favorites such as nuts and cheeses.

Furthermore, other amino acids found in turkey compete with tryptophan. Eating turkey along with carbohydrates blocks competing amino acids and may favor the delivery of tryptophan into the brain. However, it is more likely the fact of eating a high-calorie meal that causes the holiday nap.

Does Tryptophan Help You Sleep?

Some studies have found that consuming a diet rich in tryptophan can improve sleep quality and lead to less time spent awake in bed. Including more tryptophan in the diet also boosts levels of melatonin and serotonin and may help reduce the time it takes to fall asleep. Lower doses of tryptophan may improve sleep during the slow-wave stage of your sleep cycle, and some people with obstructive sleep apnea have reported significant improvements after consuming tryptophan.

Some studies have noted additional positive outcomes for people who consume a naturally tryptophan-rich diet compared to those whose tryptophan intake is relatively low. These outcomes include less irritability, improved mood, and reduced anxiety.

The average American diet contains more than enough tryptophan, but some people choose to take tryptophan supplements to treat symptoms for a wide range of conditions, such as insomnia, depression, and premenstrual symptoms.

Are Tryptophan Supplements Safe?

L-tryptophan supplements are considered potentially safe for short-term use of three weeks or less. Potential side effects of L-tryptophan supplements include headaches, blurry vision, drowsiness, stomach pain, diarrhea, or vomiting. L-tryptophan supplements have not been extensively studied and more research is needed to pinpoint why and how they affect the body.

L-tryptophan supplements may interact with certain other medications and produce some undesirable side effects. People who take L-tryptophan supplements along with medications, herbs, and supplements that have sedative properties may experience breathing problems and excessive sleepiness. Issues may also arise with serotonergic medications, herbs, and supplements, since they – like L-tryptophan supplements – can increase serotonin production. Excessive serotonin levels can lead to vomiting, seizures, and heart problems.

L-tryptophan was the subject of controversy in 1989, when the supplements were linked to roughly 1,500 cases of a neurological condition known as eosinophilia-myalgia syndrome (EMS). The outbreak was eventually blamed on a contaminated supply of supplements that originated from a single source, and the FDA lifted the ban in 2005.

It is important to speak to your doctor before taking tryptophan supplements.

About The Author

Dr. Michael Breus

Clinical Psychologist, Sleep Medicine Expert

Michael Breus, Ph.D is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. He holds a BA in Psychology from Skidmore College, and PhD in Clinical Psychology from The University of Georgia. Dr. Breus has been in private practice as a sleep doctor for nearly 25 years. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is also the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan, Good Night!, and Energize!

  • POSITION: Combination Sleeper
  • TEMPERATURE: Hot Sleeper

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