According to Ralston's perspective, what is happening to time?

In the beginning of his entrapment, Ralston feels the night go by quickly. However, as time progresses in a state of insomnia, Ralston's world slows to a halt. The night becomes colder and longer. He transitions between trances but in his moments of reality, time is slowing. With the same songs and thoughts occupying his mind, waiting to be rescued and no longer actively trying to escape, time is as slow as the blood that thickens in his body.