There are many reasons for sudden fainting and loud snoring, such as cerebrovascular disease and epilepsy. 1. Epilepsy: when elderly people suddenly faint and snore loudly, it may be caused by epileptic seizure, muscle spasm occurs during the seizure, which may cause loud snoring during fainting. 2. Cerebrovascular disease: when some cerebrovascular diseases occur, sudden fainting and loud snoring may also occur, such as cerebral hemorrhage, cerebral ischemia and so on. When cerebral hemorrhage occurs, if the amount of bleeding is large, the brain stem of the brain will be compressed, which will affect the normal physiological function of many systems, and the respiratory function is also likely to be one of them. 3. Other: when poisoning, hypoglycemia, trauma and other causes of nerve center dysfunction, there may also be a sudden fainting and loud snoring. Sudden fainting, loud snoring may also be other reasons, people around should immediately call 120 emergency telephone, timely medical treatment.