Beauty sleep is a real thing. Researches have shown that people who have enough sleep look more attractive to others.

A few bad nights is enough to make a person look “especially” more ugly, their sleep experiments(实验) show.

The researchers asked 25 university students to join in their sleep experiment. They were asked to get a good night’s sleep for two nights.

A week later, they were asked to sleep for only four hours every night for two nights in a row.

The researchers took make-up free (素颜) photos of the volunteers after both the good and the bad sleep.

Next, they asked 122 strangers to have a look at the photos and judge (评价) them on attractiveness, health, and sleepiness, as well as asking them: “How much would you like to make friends with this person in the picture?”

The strangers were good at judging if the person they were looking at was tired, and, if they were sleepy, their attractiveness score was low.

The strangers also said they wouldn’t want to communicate with the tired students. The researchers say this is natural for people. ▲ In other words, people don’t want to stay long with people who might be ill.

Dr. Brewer, an expert at the University of Liverpool said: “Judgement of attractiveness is often unconscious (无意识的), but we all do it, and we are able to judge on even something small like whether someone looks tired or unhealthy. This study is a good reminder of how important sleep is to us.”

We know many musical instruments well, such as pianos, violins, drums and so on. What about the erhu? The erhu is a traditional Chinese instrument. It is the most popular of the huqin family, and it has a long history.

The modern erhu developed from the xiqin, which was played by many ethnic minorities (少数民族) during the Tang Dynasty. In the Song Dynasty, musicians began to use the erhu to perform different kinds of music, and it became quite a popular instrument. The art of the erhu developed quickly during the Ming and Qing Dynasties. It became an important instrument in different folk music. At present, it is used in both traditional and modern music, such as in pop, rock and jazz. It has even become a solo (独奏) instrument. One of the most famous musical pieces played on the erhu is Erquan Yingyue.

As the erhu was mainly played by common people and the playing skills were passed down orally (口头地), there are few written records about the erhu that can be found. To study the history and the development of the erhu, scientists usually turn to ancient paintings. The earliest pictures of this instrument were found in Gansu Province, where five erhu pictures were discovered on murals (壁画).