Though it is possible to die from this, it is highly unlikely that anybody's body will allow them to get to that point. It varies from one person to the next, but the average human will/can experience fatigue, nausea, restlessness, and lightheadedness after 48 hours of no sleep. By the 72 hour mark, those symptoms can build up to audial, visual, and other basic sensory hallucinations. Though after roughly 96 hours of uninterrupted conciousness, the body will usually shut itself down, as a defense mechanism, or will begin to experience bouts of unconciousness. Whereas most people will fall asleep and stay asleep after 96 hours of no sleep, some people may fall asleep for a matter of moments and do this off and on until the body is recharged enough to stay awake for more than 5 minutes or so. The heart, brain, and lungs all are run by the medula oblongata, and without sleep, this part of the brain will "reset" the whole body to assess how much actual recooperative sleep is needed to maintain involuntary funtions. Of course, I'm not a doctor, so what the hell do I know.