Does milk have melatonin in it? The science behind milk and sleep

November 21, 2025 •

4 min read

According to the Centers for Disease Control and Prevention, approximately one in three adults in the United States does not get enough sleep. In the quest for better rest, many turn to time-honored remedies like a warm glass of milk, prompting the question: does milk have melatonin in it?

Quick Summary

Milk contains trace amounts of melatonin, with significantly higher levels found in milk collected during the night. Other compounds like tryptophan and calcium also aid sleep.

Key Points

Night Milk contains more melatonin: Milk collected at night can have melatonin levels several times higher than milk from daytime milking.
Standard milk has trace melatonin: While some melatonin is present in all milk, the amounts in a single glass of standard dairy milk are very low and unlikely to have a major sedative effect.
Tryptophan is a key ingredient: Milk's high tryptophan content is converted by the body into serotonin and then melatonin, a key pathway for regulating sleep.
Psychological comfort matters: The ritual of drinking warm milk before bed provides a powerful psychological cue for relaxation that can help improve sleep quality.
Other nutrients play a role: The calcium and magnesium in milk assist in the synthesis of melatonin and support muscle relaxation, further aiding sleep.
Bioactive peptides found: Specific peptides derived from milk proteins can have sedative and anti-anxiety effects by interacting with brain receptors.

Yes, milk contains melatonin, but the amount depends on the time of day it was collected.

While the classic folk remedy of drinking warm milk before bed has persisted for generations, modern research confirms there is a scientific basis for its sleep-promoting reputation. Milk is not just a source of calcium and protein; it also naturally contains melatonin, the hormone that helps regulate your body's sleep-wake cycle. However, not all milk is created equal when it comes to melatonin content. The amount varies significantly depending on when the dairy animals were milked.

The "Night Milk" Phenomenon

Cows, like humans, produce more melatonin in darkness to signal that it is time to sleep. Research has shown that milk collected during nighttime milking, sometimes called “night milk,” contains a much higher concentration of melatonin than milk collected during the day.

Higher Melatonin Levels: Night milk can contain melatonin concentrations that are significantly higher than milk from daytime milking. These higher levels are a direct result of the cow's natural circadian rhythm.
Fortified Milk: In some countries, fortified milk products are commercially available that use special dairy management techniques, such as keeping the cows in darkness during milking, to boost melatonin content naturally.

More than just melatonin: Tryptophan and other sleep-supporting compounds

Melatonin is not the only reason milk is associated with sleep. It also contains other compounds that support rest.

Tryptophan: Milk is a good dietary source of tryptophan, an amino acid that the body uses to produce serotonin, a neurotransmitter that promotes relaxation. Serotonin is then converted into melatonin by the pineal gland.
Calcium and Magnesium: Dairy products are rich in minerals like calcium and magnesium, which act as cofactors in the enzymatic process that converts tryptophan to serotonin and melatonin. Magnesium is also a known muscle relaxant.
Protein and Peptides: The casein protein in milk breaks down into bioactive peptides, which have demonstrated sedative and anti-anxiety effects in animal studies by binding to GABA receptors in the brain.

The psychological effect and other factors

In addition to its nutritional content, the ritual of drinking milk before bed can also play a significant role in promoting sleep through psychological conditioning.

Comforting Routine: For many people, drinking a glass of milk (especially warm milk) is a comforting habit that signals to the brain that it is time to wind down. This association can help relieve anxiety and prepare the mind for rest.
Warmth: While studies have not definitively proven that warm milk is better than cold milk for sleep, the act of sipping a warm beverage is a well-known relaxation technique.
Placebo Effect: The belief that milk will help you sleep can be a powerful psychological tool. The placebo effect can help quiet the mind and reduce the time it takes to fall asleep.

Comparing Melatonin Levels in Milk

To illustrate the difference in melatonin content, the table below summarizes findings from various studies on milk from different milking times.


Milk Type	Melatonin (pg/mL)	Milking Time and Conditions	Source
Night Milk (High)	~39.4	Nighttime milking, Holstein cows
Night Milk (Low-light)	~163.1	Nighttime milking, 1-week total darkness
Day Milk	~4.0	Daytime milking, Holstein cows
UHT Processed	No significant loss	Total herd milk, UHT treatment

Other foods rich in melatonin

While milk contains sleep-supporting compounds, other foods offer much higher concentrations of melatonin.

Tart Cherries: A well-known natural source of melatonin, tart cherry juice has been shown in studies to improve sleep duration and quality.
Almonds and Walnuts: These nuts contain natural melatonin, along with other sleep-friendly nutrients like magnesium and omega-3s.
Kiwi Fruit: Studies have shown that eating kiwis before bed can improve sleep onset and duration.
Oats and Goji Berries: Whole oats and goji berries are also notable for their naturally high melatonin content.

Conclusion: The power of milk for sleep is multifaceted

In summary, milk does contain melatonin, particularly in higher concentrations when collected from animals milked at night. However, the amount of melatonin in a single glass of standard milk is very small compared to supplements and is unlikely to be the sole reason for a restful night. Milk's ability to promote sleep is a combination of factors, including its tryptophan and calcium content, the presence of calming peptides, and the psychological comfort of a warm beverage and a consistent bedtime routine. For those seeking better sleep, milk can be a beneficial part of a holistic approach that also includes good sleep hygiene and a balanced diet. For persistent issues, a doctor's advice is recommended. Research continues to explore the exact mechanisms, such as the potential role of dairy on the gut microbiome, which may also influence sleep quality. For more on the role of nutrition in sleep, see this extensive review from the National Institutes of Health.(https://pmc.ncbi.nlm.nih.gov/articles/PMC10229376/)

Frequently Asked Questions

The amount of melatonin in milk is very low. A single 240ml cup of regular cow's milk contains only trace amounts, typically in the picogram range (e.g., 240 to 960 pg), which is not enough to induce a sedative effect.

No, 'night milk' is not the same as regular milk. It is milk specifically collected from cows at night under dark conditions, leading to a significantly higher melatonin content. Some companies market these special dairy products.

Warming milk does not increase its melatonin content, as melatonin is stable during heat treatment processes like pasteurization. The benefit of warm milk is likely psychological, as it can be soothing and signal to the body that it is time to relax.

Plant-based milks like soy milk do not naturally contain melatonin from a biological process, but they can contain tryptophan and other nutrients that aid sleep. Some may be fortified with additional compounds.

No, standard milk does not contain nearly enough melatonin to serve as a treatment for insomnia. The amounts are negligible compared to dosages used in supplements. Milk is better seen as a supportive part of a healthy diet and bedtime routine.

Milk contains tryptophan, an essential amino acid. The body uses tryptophan as a precursor to create serotonin (a mood regulator) and melatonin (the sleep hormone), which both play key roles in regulating sleep.

Research has not shown a significant difference in sleep benefits between drinking milk hot or cold. The advantage of a warm beverage is primarily its calming, psychological effect, which can help you relax before bed.