Turkey makes you sleepy from tryptophan
Turkey contains the amino acid tryptophan, which is involved in producing serotonin and melatonin, but a typical serving does not contain enough tryptophan to cause measurable drowsiness. Post-meal fatigue after holiday meals is better explained by large portions, high carbohydrate intake, and alcohol consumption.
What we know
Tryptophan is an essential amino acid that serves as a biochemical precursor to serotonin and melatonin, both of which influence mood and sleep regulation. The popular belief links this pathway to turkey-induced sleepiness. However, the connection breaks down on several counts.
First, turkey contains no more tryptophan than many other common protein foods. Chicken, beef, salmon, cheddar cheese, and pumpkin seeds all have comparable or higher concentrations. Yet none of these carry the same sleepy reputation. Second, the amount of tryptophan in a typical serving of turkey, around 200 to 250 mg, is far below the doses used in clinical studies demonstrating sleep effects, which typically involve 1,000 mg or more taken on an empty stomach.
Third, when protein-rich foods are consumed, the many amino acids they contain compete with tryptophan for transport across the blood-brain barrier. This competitive inhibition actually limits how much tryptophan reaches the brain after a protein-heavy meal. Paradoxically, a carbohydrate-rich meal creates a more favorable environment for tryptophan absorption because insulin drives competing amino acids into muscle tissue.
The real causes of post-holiday drowsiness are overeating, a large carbohydrate load from side dishes and desserts, and alcohol. A large meal diverts blood to the digestive system and triggers hormonal signals that promote satiety and relaxation. These factors collectively explain post-meal fatigue far better than tryptophan content in turkey.
Common claims
- Turkey contains uniquely high tryptophan levelsFalse - similar to other meats
- Dietary tryptophan causes post-meal sleepinessFalse at normal serving sizes
- Tryptophan is linked to serotonin and melatoninTrue, but doses matter
Evidence hierarchy
All sources
- Turkey Doesn't Make You SleepyMcGill Office for Science and Society · 2024
- Why Does Turkey Make You Sleepy? It Actually Doesn'tHealthline · 2020
- Influence of Tryptophan and Serotonin on Mood and CognitionNutrients (PMC) · 2016
- The Turkey-Tryptophan ConnectionTexas Health Resources · 2023
- Why Does Turkey Make You Sleepy? It Actually Doesn'tGoodRx · 2025