Insomnia and sleeping disorders are among the most serious problems troubling urbanites today, but a cup of "night milk" may not only help them fall asleep but may also make them become more active in the daytime.

This is thanks to the effect of melatonin, a hormone found in milk. Its level is significantly higher when cows are milked shortly before dawn--meaning before they see the light in the morning, according to a Finnish scientist and president of a company that sells the product.

"Light plays a decisive role in the level of melatonin in cow milk," said Maija Valtonen, president of Oy N-Milk Ltd. and a former professor at the University of Kuopio, where she studied the effect of "night milk."

Valtonen was recently in Japan to provide advice to Japanese farmers who have started producing night milk. It was her second visit following one about a year ago.

Melatonin is produced in the pineal gland of mammals and aids in the regulation of circadian rhythms. In cow milk, the concentration of melatonin is three to four times higher when cows are milked shortly before dawn than when they are milked during the daytime. It also has been discovered that the substance exists not only in animals but also in a variety of plants.

Melatonin has been proved to be a powerful antioxidant, helps improve sleeping disorders, alleviates jet lag and reduces the risk of cancers and lifestyle-related diseases.

The veterinarian-turned-company-president said night milk is significant in that it enables people to take in melatonin from a natural product, instead of in the form of supplements.

"Our study showed that those who regularly drink night milk are more active than those who do not," Valtonen said.

In the study on the effect of night milk, Valtonen and other researchers objectively measured rest, activity and sleep time in 12 healthy middle-aged individuals who had no sleep difficulties.

The study was conducted over four periods, in which the subjects first received either normal commercial milk or night milk for two weeks and then normal milk and two milligrams of melatonin or a placebo for another two weeks.

The overall result of the test showed that people's activity increased significantly when they consumed night milk.

Valtonen recommended consuming three glasses of night milk a day but added that sensitivity to melatonin varies greatly according to individuals.

Sleep patterns are enhanced and daytime activities increased with long-time use, according to the scientist.

A study on rats indicated the risk of taking excessive amounts of melatonin, a danger associated with taking the substance in pill form rather than in natural products such as milk.

According to the study, which examined a total of 30 rats for 32 months, a group fed night milk lived longer than those given ordinary milk. However, the test also showed that those fed with milk that had 20 times the natural concentration of melatonin died earlier than those fed with night milk with natural melatonin levels. Postmortem examination showed the group of rats fed with the highest level of melatonin had enlarged livers.

From scientist to president

Valtonen studied natural sciences in the College of Veterinary Medicine at the University of Helsinki.

She began research on melatonin in 1980, but it was in 1990 that she started studying the substance in milk.

"At first I studied melatonin in relation to research on fur because the substance is closely related to fur quality," said Valtonen, who served as director of research and development at the Finnish Fur Breeders Association from 1981 to 1990.

She became focused on melatonin in milk while studying the substance in various animals. While researchers usually extract melatonin from animals' blood and urine, it was easier to extract the substance from milk when studying cows.

After working as professor of veterinary sciences and reproductive physiology at the University of Kuopio between 1990 and 2002, she became president of Oy N-Milk, which cooperates closely with the university in the production of night milk.

Currently, 19 farmers in Finland produce a total of 1 million liters of Night Milk brand every year. Though the brand costs about 20 percent more than regular milk, it always sells out. The president hopes to increase the number of farmers to four times the current figure in a few years.

Finland produces 2.3 billion liters of milk annually, or 440 liters per capita. Night milk consumption accounts for about only 0.04 percent of the total milk consumption in Finland.

"I myself consume about two liters of milk every day," Valtonen said, adding that milk is used in various forms of cooking in the country.

In Japan, some companies have started selling similar products.

While such products are gradually gaining recognition in Japan, there are difficulties in raising dairy cows the way they do in Finland.

For instance, Valtonen recognized a difference in the design of shelters for cows in both countries due to the difference in climate.

"Dairy barns in Finland usually have walls, whereas there are no walls in Japan," she said. "It may be difficult to strictly control light in a barn without walls."

Valtonen believes drinking night milk has a good effect on her own health.

"Considering my age, I think I stay healthy and active thanks to the night milk," she said.