Hey, I just watched the Machinist ( http://www.imdb.com/title/tt0361862/ ) after this forum recommended it. I just didn't understand one thing about it: Why did Reznik wash his hands with bleach so much? He had to have done it at least 5 times throughout the movie, yet I didn't understand exactly why. Does anyone here know?
The simple answer was that his insomnia (among other things) was causing things such as paranoia, delusions, hypochondria and OCD, seeing as how he spent hours cleaning everything. The artistic answer was that in the back of his mind he knew he killed the young boy and he metaphorically had blood on his hands he was constantly trying to wash off with the bleach.
The 2 answers can be fairly compatibly combined.
The above taken from the "frequently asked questions" on the very imdb page you linked in the OP