According to clinical evidence, when people sleep, the immune system is in a state of depression. At this time, viruses, bacteria and harmful substances are more likely to enter, invade and harm the human body. In addition, when people lie in bed, especially at night, they have the habit of closing doors and windows, which makes the air in the bedroom relatively closed, and the continuous emission of harmful gases and substances can not be timely and fully diffused. The concentration is often much higher than that when the window is opened in the daytime. These high concentration pollutants will cause serious harm to human health . Therefore, it is recommended to move the machine to the bedroom at night, so that clean air can accompany you to sleep easily.