How Protein Affects Your Sleep?

Can what you eat at dinner change how well you sleep? Here is what research says about protein, tryptophan and bedtime snacks, and a 7-day test you can run yourself.

In this article

1. Does protein affect sleep?
2. What does tryptophan have to do with sleep?
3. Is a protein snack before bed a good idea?
4. How long before bed should you eat a protein-rich dinner?
5. How can you test protein and sleep on yourself?
6. Who should be careful with protein and sleep advice?
7. Frequently asked questions
8. Final thoughts
9. Sources and further reading

Does protein affect sleep?

Protein may affect sleep modestly, but the research does not prove that eating more protein will make you sleep better. Studies on protein and sleep point in a hopeful direction, yet most are observational or small, and results vary between studies. Protein is one piece of a bigger picture.

Alcohol with dinner is another common variable, covered in how alcohol changes sleep quality.

What the reviews found

A 2020 systematic review and meta-regression in Nutrients (Sutanto and colleagues) analysed 19 studies. It found that people who slept well, defined as 7 or more hours with good sleep efficiency and short sleep latency, got a higher share of their daily energy from protein than poor sleepers. Their carbohydrate and fat shares were lower.

The authors noted that more rigorous trials are needed and that cause and effect could run the other way.

A separate 2020 narrative review in Nutrients (Binks and colleagues) looked at diet and sleep in healthy adults. It reported mixed results for protein. One study found fewer wake episodes after high-protein meals, while another found better sleep on a diet with 20% of energy from protein than on diets with 10% or 30%. The authors said the studies were too different from each other to combine statistically.

What the controlled trials found

The strongest direct evidence comes from two feeding trials by Zhou and colleagues, published in 2016 in the American Journal of Clinical Nutrition. The first had 14 participants and the second had 44, all overweight or obese adults on calorie-restricted diets. In the second trial, people eating 1.5 grams of protein per kilogram of body weight had better sleep scores by week 16 than people eating 0.8 grams per kilogram (4.0 versus 5.9 on a scale where lower is better).

These trials were small and specific to people losing weight, so they may not apply to a healthy adult who is not dieting.

What a community study adds

A 2022 cross-sectional study in Frontiers in Nutrition studied 104 healthy adults aged 50 to 75 in Singapore. Total protein intake showed no significant link with sleep latency or efficiency. Sleep duration was linked with dietary tryptophan relative to other large amino acids, especially from plants, but a snapshot cannot show cause.

What does tryptophan have to do with sleep?

Tryptophan is an amino acid that the body uses as raw material for serotonin, which feeds into melatonin, so it is part of the sleep story. The link between a tryptophan-rich meal and sleepiness is far weaker than popular claims suggest, because the body regulates this pathway tightly.

Binks and colleagues reported that in tryptophan depletion studies, a completely tryptophan-free drink reduced total sleep time and sleep efficiency compared with a partly tryptophan-free drink. That suggests the body needs adequate tryptophan, not that extra amounts become a sedative. Some small studies of tryptophan-containing foods reported better sleep measures.

Harvard Health makes a related point: the synthesis of serotonin is tightly regulated, so eating extra tryptophan does not reliably raise serotonin in the brain. Adults need roughly 250 to 400 mg of tryptophan a day, and a normal varied diet usually supplies it.

Is a protein snack before bed a good idea?

A small protein snack before bed does not appear harmful for most healthy people, but the evidence on sleep itself is thin. Most pre-sleep protein research was designed to study muscle and metabolism, not sleep, so it cannot tell you whether a snack will help you sleep.

A 2015 review in Nutrients by Kinsey and Ormsbee concluded that small evening intakes, around 150 kcal, whether a single nutrient or a mixed snack, do not appear to be harmful. Studies in young and older men found that about 40 g of casein protein (160 kcal) before sleep supported overnight muscle protein synthesis. The review did not set out to test sleep quality, so these findings should not be read as a sleep benefit.

The same review linked large mixed meals, and eating most of your daily food late in the evening, with worse outcomes, particularly in shift workers and people with night eating syndrome. In practice, the size of the evening meal appears to matter more than whether it contains protein.

A concrete example

If you wake hungry after an early dinner, a small snack such as yogurt may be reasonable. A second full dinner at 10 p.m. is more likely to leave you uncomfortable.

How long before bed should you eat a protein-rich dinner?

There is no research-proven cutoff for protein-rich dinners, but health agencies suggest leaving a few hours between a large meal and bed. The US National Heart, Lung, and Blood Institute advises avoiding heavy or large meals within a few hours of bedtime, while light snacks are acceptable. The NHS gives a more specific range for people with night-time heartburn.

The timing question reaches beyond protein. whether eating late at night hurts your sleep covers meals more broadly.

The NHS recommends avoiding food and drink within 3 or 4 hours of bed, and eating smaller, more frequent meals rather than large ones. That advice is aimed at heartburn and acid reflux, but it is a sensible starting point if you notice discomfort at night. The NHLBI also notes that caffeine effects can last up to 8 hours, so check shake labels.

How can you test protein and sleep on yourself?

You can test protein and sleep on yourself by changing one eating habit for a week while keeping bedtime, caffeine and alcohol steady. A single good or bad night proves nothing, so the goal is to look for a pattern across several nights, and to treat a lack of change as a useful result too.

Other evening habits can blur the picture, caffeine among them. See does caffeine really ruin your sleep?

Who should be careful with protein and sleep advice?

People with kidney disease, reflux, diabetes, pregnancy or regular medication use should ask a healthcare professional before changing protein intake or evening eating. General findings from healthy or weight-loss groups may not apply, and a few situations need individual guidance.

Medical conditions and medicines

Anyone with kidney disease is often given individual protein targets, so adding protein without advice may be unwise. Evening eating is also managed carefully in some people with diabetes, and Kinsey and Ormsbee note that bedtime feeding is essential for some people with type 1 diabetes. Follow your care team rather than general articles.

Tryptophan supplements are a separate matter from food. They can interact with some medicines, including certain antidepressants, so speak to a doctor or pharmacist before trying them.

Pregnancy and night-time heartburn

Pregnancy changes nutritional needs and digestion, so ask your midwife or doctor about evening meals. The NHS advises seeing a GP if you have heartburn most days, lifestyle changes are not working, or you have difficulty swallowing, frequent vomiting or unexplained weight loss.

When sleep trouble is not about food

For long-running poor sleep, loud snoring, gasping at night or disruptive daytime sleepiness, protein is unlikely to be the answer. Talk to a doctor or sleep specialist.

Frequently asked questions

Can eating too little protein make you sleep worse?

Possibly, but the evidence is indirect. Studies link a higher share of energy from protein with better sleep in some groups, and the reviews note that results are mixed and may reflect reverse causality. Eating adequate protein is good for general health anyway, so aim for a balanced diet.

Do protein shakes at night keep you awake?

Protein shakes are not known to keep most people awake, but individual responses vary. A large or sweet shake may feel heavy before bed, and some flavoured products contain caffeine. Check the label, and try a smaller serving a few hours before bed if you feel uncomfortable.

Should I take a tryptophan supplement for sleep?

Speak to a doctor or pharmacist first. Harvard Health notes that extra tryptophan does not reliably raise brain serotonin, and supplements can interact with some medicines, including certain antidepressants. Most adults already get the 250 to 400 mg a day they need from a varied diet.

Is plant or animal protein better for sleep?

No one has shown that either is better. In the 2016 feeding trial, higher protein improved sleep scores independent of the protein source. The 2022 Singapore study linked sleep duration with tryptophan from plant foods, but it was cross-sectional, so choose foods you enjoy and digest well.

Why do I feel sleepy after a big meal?

Harvard Health attributes post-meal sleepiness mainly to digesting a big meal and, on holidays, to alcohol served alongside. It is not specific to turkey or tryptophan. If heavy dinners leave you uncomfortable, try a smaller portion and an earlier finish time.

Can poor sleep change how much protein I want to eat?

Possibly. The 2020 meta-regression noted that the link between diet and sleep may run in both directions. Short or poor sleep may change what and how much people eat, which makes it hard to know whether food shaped sleep or the other way round.

Final thoughts

Here is the short recap.

• Protein may influence sleep a little, but the evidence is mixed and mostly observational.
• The "turkey coma" is a myth, since turkey has about the same amount of tryptophan as chicken or beef.
• A moderate amount of protein at dinner is usually fine, while a very large late meal is more likely to cause trouble.

Your turn: What does your usual dinner look like, and have you noticed it affecting your sleep? Tell us in the comments.

Sources and further reading

1. Sutanto CN, Wang MX, Tan D, Kim JE. Association of Sleep Quality and Macronutrient Distribution: A Systematic Review and Meta-Regression. Nutrients, 2020.
2. Binks H, Vincent GE, Gupta C, Irwin C, Khalesi S. Effects of Diet on Sleep: A Narrative Review. Nutrients, 2020.
3. Zhou J, Kim JE, Armstrong CL, Chen N, Campbell WW. Higher-protein diets improve indexes of sleep in energy-restricted overweight and obese adults: results from 2 randomized controlled trials. American Journal of Clinical Nutrition, 2016.
4. Sutanto CN, Loh WW, Toh DWK, Lee DPS, Kim JE. Association Between Dietary Protein Intake and Sleep Quality in Middle-Aged and Older Adults in Singapore. Frontiers in Nutrition, 2022.
5. Kinsey AW, Ormsbee MJ. The Health Impact of Nighttime Eating: Old and New Perspectives. Nutrients, 2015.
6. Harvard Health Publishing. The Turkey Coma: Fact or Fiction?. Harvard Health, accessed 2026.
7. NHS. Heartburn and acid reflux. nhs.uk, accessed 2026.
8. National Heart, Lung, and Blood Institute. Healthy Sleep Habits. NIH, accessed 2026.