The Welt am Sonntag weekly paper reported on Sunday that the firm Milchkristalle was launching its products which it says are a natural way of providing melatonin, which is rarely found in foods.
The hormone is sold in the US, the paper reported, but added that in Europe it is classified as a medicine and can only be obtained when prescribed by a doctor.
Melatonin helps regulate the body clock, entering the bloodstream when it is dark, and stopping again when it becomes light, prompting people to wake up.
The cows used to produce the night milk are kept under altered night and day conditions, with stalls brightly lit during the day and then red, orange and yellow lighting at night.
“One cannot simply switch off all the lights,” said Milchkristalle manager Tony Gnann. “Then the animals lose all orientation.”
The red-tone lighting at night means the animals remain content and can be milked, without the crucial melatonin levels dropping.
The cows' food is enriched with clover, which contains high levels of tryptophan, from which melatonin is created in the body.
The cows are then milked between 2 am and 4 am, producing milk containing up to 25 times the normal levels of melatonin, the company says.
The milk is then turned into a crystalline powder so it can be transported and stored more easily. Taken mixed with milk or yoghurt an hour before going to bed, the firm claims it can help people sleep.
Heiko Dustmann, an agricultural engineer with the Weihenstephan consultancy firm, said the melatonin can cross over the blood-brain barrier because it remains held within the milk chemicals.
He said a test on 40 people showed they found it improved their ability to fall asleep and that they woke up more easily having taken the night milk.
The idea has been criticised by a number of scientists, not least authors of the magazine Gute Pillen – Schlechte Pillen - or "Good Pills, Bad Pills," who wrote this summer that the night milk crystals were "nothing more than expensive placebos."
The independent magazine wrote that non-milk based melatonin pills did not work well, and that they contained much more melatonin – two milligrams - than the night milk crystals.
“In order to get the same amount of melatonin in the form of night milk crystals, one would have to swallow two million portions,” the authors wrote.