A friend back at home once described to me the way that he feels about going camping or hiking or on any sort of adventure. He told me that when he's home, he gets caught up in his life and the world around him, and that he really only feels "sober" when he makes a trip into the woods. This is a guy who experiments a lot with substances, so when he used the word "sober" it felt pretty literal for his situation. Of course he is not always intoxicated, but I think I understand what he meant when he said this. For him, going and becoming part of the natural world is something of a healing process.
I can see a parallel between the insight of my friend and the story recounted in "The Devil's Thumb." I don't mean to assume that Krakauer was experiencing problems using or misusing substances. Krakauer does make references to spending time at "Tom's Tavern" (4), as well as his friends telling him that he was "smoking too much pot" (7), but more than physical substance use I think that Krakauer felt a desire to go on an adventure to heal what he saw as the problems in his life. He tells the audience that he recently graduated college with little distinction and little skill, and he had experienced a messy end to his long relationship. It seems to me that Krakauer is using his adventure to the Devil's Thumb as something of a sobering up process. Although ultimately he returns to his previous job, I imagine that having an adventure that completely distracted him from him problems could have sobered him up a little bit and made him more capable of dealing with his own life.