Beauty sleep is a real thing, researches have shown that people who have enough sleep look more attractive(有魅力的) to others.

　　A few bad nights is enough to make a person look "especially" more ugly, their sleep experiments 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 socialize with the tired students. The researchers say this is natural for people. An unhealthy-looking face makes people run away. In other words, people don’t want to hang around 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), hut 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."