Dear Welcome to HCM We understand your concerns I went through your descriptions. I think your description is not full. You should have mentioned your age and any other medical conditions you might have. You became unconscious, to be true. To become unconscious, body needs to be so tired or has some organic change. It is shut down and restart because body was unable to cop with some internal or external situation. Ascertain it. Think clearly. You will get an answer. Normally this happens after severe flu or fever, high or low BP, high or low sugar level etc (there are so many other conditions also). Don t read too much into the above paragraph. Consult a general practitioner and get things confirmed. Hope this answers your query. Available for further clarifications. Good luck.