Thank you for your query. Would you please clarify a few things for me? 1)Does he have diabetes, hypertension, heart disease or seizure disorder? 2)when you say he collapsed, did he fall on the floor, or was sitting? 3)were his eyes closed or open? Did he have jerky movements of his body, limbs, eye, head? 4)when he came to, did he seem disoriented or weak or sleepy? Your description of the symptoms indicate a syncope (loss of consciousness). A syncope occurs when the blood flow to the brain has been cut off or significantly reduced. This could occur in heart disease, stroke. When the blood supply is compromised, most of brain functions don t work or sensory information from the sense organs and periphery don t get relayed to the brain centers due to the lack of oxygen. Seizures occur when is nerve tissue damage either due to reduced blood flow, infection of the brain, edema (swelling) of the brain, Mass effect (compression of brain due to a tumor or edema or blood). The neurons in the brain usually follow a fixed signal path to relay the signals to and from the rest of the body. During a seizure, these don t follow the path and go haphazardly (like a traffic jam when the traffic lights don t work). This leads to jerky movements either focally or generally and may lead to loss of consciousness. In either scenario, he wouldn t have been able to hear or respond. He needs to have a full cardiac workup (Electrocardiogram, echocardiogram, Holter monitoring), CT scan of the brain to rule out a stroke or other causes, an EEG - electroencephalogram (looks for seizure activity). I recommend seeing his physician to isolate the cause. The above mention symptoms are usually but not necessarily present. A seizure could present as just staring into space or a vacant expression. A stroke occur transiently, causing symptoms briefly before coming back with permanent damage. It is vital to find the cause and treat it early. Please accompany him and don t let him drive. If he develops Seizures, has chest pain, sweating, loss of consciousness, giddiness or severe headache, visit the ER right away. Hope this helps. Wish you both good health. Please get back to us if you have further questions