As anyone who has suffered from insomnia knows well, drinking a glass of warm milk doesn’t always help. But it might, a new study reports, if the milk is taken from a cow at night.

According to an animal study in the Journal of Medicinal Food, night milk – literally milk collected from a cow at night – contains high amounts of tryptophan and melatonin, supplements proven to aid sleep and reduce anxiety.

“Considering the fact that tryptophan and melatonin are abundant in night milk, it is possible that the sedative effect of night milk may be attributable to these substances,” the study authors wrote.

Researchers from Sahmyook University in Seoul, South Korea, fed lab mice doses of dried milk powder from cows milked both during the day and night mixed with water. Mice that received night milk, which contained 24% more tryptophan and about 10 times as much melatonin, were less active than mice that were given day milk.

These mice were also more inclined to explore open spaces, a measure that reflected reduced anxiety. These effects were comparable to the effects of diazepam, a sedative commonly used to treat anxiety.

The effects of night milk have not yet been tested on people, although many people take melatonin supplements and drink milk to aid sleep. The concept, however, is not new.

In 2010, German company Milchkristalle GmbH patented “nocturnal milk” and produced a powder from milk collected between the hours of two and 4am.

“Conditions for the cows have to be just right – light in the day and very low light conditions at night,” said Tony Gnann, a company manager, told the Guardian in 2010. The company claims its “night milk crystals” are naturally rich in melatonin.

At the time, Maike Schnittger, a Hamburg resident, said taking the powder helped her get through a bad patch of insomnia and anxiety by helping her fall asleep within half an hour.

“It was a deep sleep and the next morning I felt really awake,” she told ABC News. “I didn’t ever take medicine for sleeping and I don’t want to.”

Although at first, Carl Bazil, director of the epilepsy and sleep division in Columbia University’s neurology department, was skeptical of night milk, he said the researchers had conducted the study in a “pretty responsible way”.

Since tryptophan and melatonin are proven to have sedative properties, and milk is known for helping people fall asleep, Bazil said the concept of night milk is not too far-flung.

“The theory is correct,” he said.

Bazil said it would be speculative to say that night milk could improve a person’s sleeping habits physiologically, and further research was needed to study the differences between night and day milk and its effect on people.

However, according to Bazil, treating sleep disorders involves using placebo effects. He often tells patients who have trouble with sleep to develop rituals such as winding down before bed and turning off cell phones.

“It’s a way to train yourself to sleep, and definitely a placebo effect in people,” he said. “That’s OK – if it works.”

Because drinking milk harvested at night has no known harmful effects, using it as a placebo would be fine way to train oneself to fall asleep. Bazil predicted the information from the study would cause new fads in using night milk to treat sleep disorders.

“It’s not a bad thing,” he said. “Better than everybody taking Ambien.”