ok this is simple, ive been smoking for a long time now and ive gone threw it all, ive smoked everything from 5th, to white widow. but ive smoke a halfy of some dro b4 and i thought i was gunna die.. but as u said u went to sleep and felt better.. its just ur body saying that ur getting ready to passout, now everytime u smoke.. think about how everything turned out after, ur still alive.. (u cant od on weed lol unless u eat it) plus it was kinda a bad/good idea to stay in the car.. ur high increases but. ur pretty much suffocating urself.. ive hot boxed a honda civic with the heat on and 2 water bongs going around and i passed out so think about that lol