The weather outside is not something that you can control, but the good thing is that you are able to control the humidity level in your bedroom or the entire house with a humidifier. For a healthy reasons humidity level should range between 30 and 50 percent. As an optimal humidity level for a bedroom is considered 45 to 50 percent. If you sleep in an area with a level lower than the recommended one, you may experience, irritation of the eyes, nose, and throat.