The causes of sudden blackness and dizziness are as follows: Firstly, a sudden change from a lying or squatting position to an upright position may lead to postural hypotension, which will result in blackness, dizziness and vertigo. Secondly, during a hypoglycemic attack, the patient will experience dizziness, blackness in front of the eyes, and at the same time will be accompanied by sweating, panic, hand tremor and other symptoms, usually after eating sweets, the symptoms can be relieved. In addition, in neurological diseases such as transient ischemic attack, there will be sudden blackness, dizziness and other symptoms. Finally, patients with cervical spondylosis may experience blackness and dizziness when the position of the neck suddenly changes, and may be accompanied by nausea, vomiting, and spinning of the vision and other accompanying symptoms. Therefore, when the above symptoms occur, it is necessary to consult a doctor in time to do relevant examinations, such as blood glucose tests, blood pressure, CT or MRI of the skull and cervical vertebrae, and other relevant examinations to confirm the diagnosis.