World Sleep Day falls on March 21, aiming to celebrate the benefits of good, healthy sleep and raise awareness about sleep problems and metal health. The day was introduced in China in 2003. Since then, China has held a series of cultural events on the day and drawn focus to sleep problems. More and more Chinese people who have sleep problems have begun to take their health seriously. Animals however, have certainly taken care of their sleep problems. Let's take a look at their adorable sleeping faces.