When you wake up in the morning with a muffled voice, consider dry indoor air, excessive use of the voice, poor diet, inflammation of the throat and so on. 1. Dry indoor air: If the indoor air is dry when you sleep, it will lead to the evaporation of water from the oral mucosa, which will cause the symptoms of dry throat and mute voice. 2. Excessive use of the voice: If you speak loudly or a lot during the day, excessive use of the voice, resulting in congestion of the vocal cords, can also lead to a muffled voice in the morning. 3. Poor diet: If you eat too salty or too spicy before going to bed, it will stimulate the mucous membrane of the throat, leading to congestion and edema of the vocal cords, causing a mute voice. 4. Inflammation of the throat: sleeping at night with a cold, decreased resistance, leading to germs invasion, inflammation of the throat; gastroesophageal reflux, reflux fluid stimulation of the throat, there will also be a mute voice symptoms. There may be other reasons for the mute voice in the morning, such as vocal cord nodules, polyps, tobacco and alcohol stimulation. If you experience a muffled voice frequently, it is recommended that you seek medical attention to identify the cause.