A warm drink of milk before bed has long been the best choice for those wanting a good night’s sleep. But now a study has found it really does help people nod off（打瞌睡）—if it is milked from a cow at night.

Researchers have discovered that “night milk” contains more melatonin(褪黑激素), which has been proven to help people feel sleepy and reduce anxiety（焦虑）.The study, by researchers from Seoul, South Korea, involved mice being fed with dried milk powder（奶粉） made from cows milked both during the day and at night. Those given night milk, which contained 10 times the amount of melatonin, were less active and less anxious than those fed with the milk collected during daytime, according to the study published in The Journal of Medicinal Food.

Night milk quickened the start of sleep and caused the mice to sleep longer.

While the effect of cow milk harvested at different time has not been tested on humans up to now, taking melatonin drugs has been suggested to those who have trouble falling asleep at night.

Previous （以前的）studies have also showed that milk can be excellent for helping sleep because of the calcium content, which helps people to relax.

Wind power is a very clean source of energy. This is how wind power works. Wind makes windmills spin(旋转). When the windmills spin, they make electricity. Then we can use the electricity.

A lot of people think that wind power is new, but that’s not true. For thousands of years, people have used wind to sail boats and move water. We still do those things today, but these days we mostly use wind power to make electricity.

Wind power is a very popular source of energy. Most people think that we should use it more and more. First of all, it’s clean. Windmills don’t pollute the environment at all. Second, we can use wind power forever. After all, we will always have wind. Also, wind power is cheap, and it’s getting even cheaper.

A lot of people don’t understand wind power very well. They believe that there are problems with wind power, but many of those problems are not real. For example, some people say that windmills are dangerous for birds. They used to be true, but it isn’t true anymore. Old windmills killed birds because they spun very fast. New windmills spin slowly, and they aren’t dangerous for birds.

However, there are real problems with windmills. One problem is that many people think windmills are very ugly. This is a problem for people, because windmills are often in very pretty areas. Also, wind doesn’t blow all the time, so we can’t use wind power all the time. Finally, windmills are noisy.

Wind power is becoming more and more common. Right now, more than 80 countries use wind power. About 2.5 percent of the world’s power comes from the wind. For some countries, that number is a lot higher. Wind power gives Denmark more than 25 percent of its electricity.

Soldiers and other military people wear uniforms with various other symbols to indicate their status. But in the business world everyone wears more or less similar suits, and you cannot tell at a glance who ranks higher or lower than another. So how do people in the business world show their superiority?

An attempt to study this was made by two researchers using a series of silent films. They had two actors play the parts of an executive and a visitor, and switch roles each time. The scene had one man at his desk playing the part of an executive, while the other, playing the part of a visitor, knocks at the door, opens it and approaches the desk to discuss some business matter.

The audience watching the films was asked to rate the executive and the visitor in terms of status. A certain set of rules about status began to emerge from the ratings. The visitor showed the least amount of status when he stopped just inside the door to talk across the room to the seated man. He was considered to have more status when he walked halfway up to the desk, and he had the most status when he walked directly up to the desk and stood right in front of the seated executive.

Another thing that affected the status of the visitor in the eyes of the observers was the time between knocking and entering. For the seated executive, his status was also affected by the time between hearing the knock and answering. The quicker the visitor entered the room, the more status he had. The longer the executive took to answer, the more status he had.