As I see it, this would be even more horrifying to be completely aware of your fate, as in the case of cave explorer Floyd Collins:
On January 30, 1925, after a few hours of work, Collins managed to squeeze through various narrow passageways: he claimed that he had discovered a large chamber, though this claim was never verified. Because his lamp was dying, he had to leave quickly, before exploring the chamber. He became trapped in a small passage while on his way out. He accidentally knocked over his lamp, putting the light out, and then he dislodged a rock from the ceiling, pinning his leg. It was later discovered that the rock weighed only 26½ pounds (12 kg), but it was wedged in such a manner that neither he nor rescuers could reach it.
He was trapped only 150 feet (50 m) from the entrance. After being found the next day by friends, hot food was taken to Floyd, and an electric light bulb was run down the passage to provide him light and some warmth, and he survived for over a week while efforts to rescue him were made. The cave passage used to reach Collins collapsed in two places on February 4. The rescue leaders, believing the cave to be impassable and too dangerous, began to dig an artificial shaft to reach the chamber under Collins. The 55-foot (18 m) shaft and subsequent lateral tunnel actually intersected the cave just above Collins, but when finally reached on February 17, he was found dead from exposure and starvation. Because they did not reach Collins from the rear, the rescuers still could not remove the rock from his leg. Deciding it was too dangerous to remove the body, the rescuers left it where it lay and hastily filled the shaft with debris. A doctor later estimated he had died three or four days previously, February 13, being the most likely.
http://en.wikipedia.org/wiki/Floyd_CollinsUp until the moment he mercifully (IMO) lost consciousness, Collins clung to hope that he would be rescued - communicating with rescuers and even receiving food & drink right up to the end.