The Science Behind "Night Milk," the Weird German Product That Claims to Help You Sleep


A German company, Milchkristalle GmbH, claims a product called night milk can promote better and more restful sleep. Called nachtmilch kristalle, or "night milk crystals," it's a mixture of melatonin, alfalfa and tryptophan that can be added to milk or another beverage. Besides aiding in sleep, night milk can purportedly reduce anxiety.

So does it really work? Let's break down the science behind it.

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A study from Seoul, South Korea, found that milk collected at night induced sedative effects and changed sleeping behavior in mice. The researchers gave lab mice doses of dried-milk powder in 100-milligram increments, from cows milked at day and at night, mixed with water. The night milk showed 24% more tryptophan and almost 10 times as much melatonin as the day milk. Those mice were also given pentobarbital, a medication for anxiety and insomnia, 30 minutes after trying night milk and day milk.

Tryptophan, contrary to the common Thanksgiving myth, is not a standalone sleeping agent. But tryptophan can be converted to serotonin, which contributes to feelings of happiness, and to melatonin, which promotes sleep and restfulness (as long as your stomach is empty).

And even if milk collected at night contains more tryptophan and melatonin than daylight milk, that still doesn't mean it'll put you to sleep, like a study-proven dosage of a supplement would.

One doctor told Mic he wasn't skeptical of night milk's claims so much as intrigued by a new area of research to explore.

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"It makes scientific sense that melatonin is secreted more at night," Dr. Sanjeev Kothare, professor in the department of neurology in the Comprehensive Epilepsy Center of NYU Langone Medical Center and director of pediatric sleep medicine, told Mic. "But no one has measured the melatonin and tryptophan levels in cows' milk during the day verses night."

Also, the study looked only at mice brains, not human brains, to determine whether or not night milk would have any impact on people. One problem with this research is that rats are nocturnal, Kothare stressed to Mic. Rats operate on an opposite sleep schedule to humans, so we can't be sure night milk would work the same on you and me.

Clearly, more testing is necessary to confirm the effectiveness of night milk. Researchers will need to conduct the study on humans who have difficulty sleeping. Melatonin and tryptophan levels need to be monitored during the day and night. And the subjects need to be given a couple days to wait out any placebo effect.

"People have been given multivitamins and many other things, then they're told it'll make them fall asleep," Kothare said. "You have to understand that a lot of [products] have a placebo effect."

What we do know is that night milk's active ingredient, melatonin, is proven to help you rest. "Using it in correct dosages will promote sleep," Kothare said. "Melatonin as a supplement works, no question."