Waking up with a crooked mouth may be facial paralysis. Waking up with a crooked mouth is commonly known as facial paralysis, which is usually caused by a viral infection or sudden exposure of the body to cold, or is related to auto-inflammatory immunity, known as peripheral facial paralysis. Some cases are caused by acute cerebrovascular disease, such as cerebral hemorrhage or cerebral infarction, and are called central facial paralysis. Peripheral facial paralysis refers to facial paralysis caused by lesions of the facial nerve nucleus or peripheral facial nerves, which manifests as paralysis of the upper and lower facial muscles on the side of the facial nerve paralyzed, and may be accompanied by decreased sense of taste, auditory sensitivity, and abnormalities of tear secretion and salivary secretion. Central facial paralysis is mainly caused by the central nervous system lesions of facial paralysis, manifested as facial nerve paralysis on the side of the opposite side of the upper facial muscle movement exists, wrinkle forehead, close the eyes, lift the eyebrows function is normal, while the lower facial muscles are paralyzed, can not complete the shrug of the nose, teeth, puffing out the cheeks and other actions. Waking up with a crooked mouth requires immediate medical attention from a neurologist.