Sleepy Cows Produce Sleep-Inducing Milk, Scientists Find

In a study, the night milk reduced the time it took subjects to fall asleep, and increased their duration of sleep.

Photo: Flickr/bertknot/CC BY SA 2.0

Sleepy Cows Produce Sleep-Inducing Milk, Scientists Find

Milk harvested from cows at night contains especially high levels of tryptophan and melatonin, according to a recent study

Cows that are milked at night actually produce “night milk,” containing “exceptionally high amounts of tryptophan and melatonin,” two sleep-inducing chemicals, according to study published in the Journal of Medicinal Food.

In a study that measured the sedative effects of so-called night milk on mice, researchers found that the milk was an effective at reducing anxiety behavior, and at shortening the time it took for subjects to fall asleep, and lengthening their period of slumber.

In test subjects, night milk also impaired motor balance and coordination, typical of sleep-inducing chemicals. As a control, the effects of daytime milk were also evaluated, and were not to share the same properties as milk harvested from cows at nighttime.

Historically, milk’s association with sleep has often been considered psychological, such as the memory of being given milk at bedtime as a child, but these findings suggest that, when harvested at the right time, milk actually contains beneficial chemicals that can be used to induce sleep.

We’re not yet aware if there’s any way to tell if the milk from your local market was harvest during the day or night, but the current consumer emphasis on food labeling might help the cause. 

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