Nov. 16. 2018
Written By:
McKel (Hill) Kooienga
McKel Hill Kooienga, MS, RDN, LDN

McKel Hill Kooienga, MS, RDN, LDN

Founder of Nutrition Stripped and the Mindful Nutrition Method™

What is tryptophan and does it really make you sleepy?

Tryptophan is one of the most popular and well-recognized amino acids particularly around Thanksgiving time as people eat turkey — a whole food source rich in tryptophan. But, is tryptophan the contributing factor to feeling sleepy after a Thanksgiving meal or when eating turkey?

What Is Tryptophan?

Tryptophan is an essential amino acid, which means you need to consume it in order for your body to get enough for all the processes that utilize and depend on amino acids. Nonessential amino acids are those amino acids your body can produce, meaning they’re always available kind of like a well-stocked kitchen or pantry!

Tryptophan comes in two forms, L-tryptophan and D-tryptophan, the differences between these versions is their molecule orientation.

What Does Tryptophan Do?

One of several important things to note about tryptophan is its involvement in hormone production such as melatonin, the neurotransmitter serotonin, and niacin (a B vitamin). Serotonin plays many roles in our body, especially in stabilizing moods, sleep, appetite, and digestion.

So where does all the talk about sleepiness come into play when we talk about turkey at Thanksgiving? It’s most likely the hormone melatonin. Melatonin plays a role in sleep, more specifically our sleep-wake cycle. It’s made in the pineal gland (an endocrine gland in our brain), and it’s released depending on the time of day — increasing in the evening and decreasing in the morning.

The health benefits of consuming enough tryptophan range from stabilizing mood, decreased anxiety and depression, improved sleep quality,

Whole Food Sources Of Tryptophan

Tryptophan can be found in everyday foods that you might already have stocked in your kitchen! Check out these whole food sources below that contain tryptophan per 100g:

  • pumpkin seeds contain 576mg which is 206% RDI
  • soybeans (soy foods) contains 575mg which is 205% RDI
  • poultry (chicken and turkey) contains 404mg which is 144% RDI
  • tuna contains 335mg which 120% RDI
  • oats contain 335mg which is 120% RDI
  • beans contain 115mg which is 41% RDI
  • eggs contain 167mg which is 60% RDI

Recipes that contain tryptophan:

So, what if you don’t eat any of these food sources of tryptophan, can it hinder your bodies ability to produce melatonin and serotonin to the optimal function?

In short, yes. Those who have a tryptophan deficiency or lower levels of tryptophan also are at higher risk for mood disorders like anxiety and depression. It’s best to consult with your physician or dietitian to find out if supplementing is the right choice for you, in most cases, it’s not advised. Rather try to increase food variety into your diet that contains this amino acid.

With this supplement, in particular, there is a rare disorder called EMS, that may cause issues with breathing, skin rashes, muscle pain and even death (1). In addition, taking tryptophan will likely interact with other forms of medication that increase serotonin or melatonin since tryptophan helps your body create these.


The more probable reason why people feel so sleepy after eating turkey at a Thanksgiving meal is from all the food! It’s more likely the sleepiness is coming from multiple factors such as drinking alcohol, having a busy (sometimes stressful day for some), and eating a lot of foods that people may normally not.

Not only that, larger portions that include a lot of starches (potatoes, casseroles, stuffing, pumpkin pie, etc.) and not a lot of fiber (i.e. veggies!). The larger portions combined with the food components that make up that meal — lots of starches and sugars — can create a blood sugar roller coaster which can also make you feel tired afterward.

If you’re looking for advice on how to get a good nights sleep, check out this article on nighttime routine and sleep.


What are your experiences with feeling sleepy post-Thanksgiving meal? Did you believe this nutrition myth? I’d love to hear your thoughts and experience about this and if anything, you’ll have a fun nutrition fact you can share around the table with your family this holiday season!