Sudden dizziness and sleepiness can be caused by vestibular lesions, but may also be caused by otogenic diseases, brain diseases, and systemic diseases. Common causes are as follows: 1. vestibular lesions, including vestibular neuronitis and vestibular abnormalities. 2. brain diseases, including brainstem and cerebellar hemorrhage, infarction and occupying lesions. 3. otogenic diseases, including Meniere’s syndrome, benign paroxysmal positional vertigo and auditory neuroma. 4. cervical spondylosis, vertebral artery cervical spondylosis, can also cause sudden dizziness. 5. systemic diseases, including Hypertension, hypotension, hypoglycemia, ketoacidosis, carbon monoxide poisoning, fever, etc. can cause sudden onset of dizziness and poor mental health in patients.