sleep depravation + flimsy plot (spoilers)
I thought that the WHOLE idea of him having insomnia was kidna cool, but it doesn't affect ANYTHING in the movie. well the ONLY thing it changed is that during the last half of the movie he had to look tired...big deal..didn't confune him to make him shoot his partner or anything remotley like that. and that's the name of the movie.
They could've TOTALLY omitted the insomnia part from the movie and have the EXACT same movie.
oh, and one more thing that is a little sidenote..why did he even hide the fact that he killed his partner? there was IMENSE fog, one of his homies was shot already, and his partnet was running RIGHT AT HIM (regradless of whether or not he MEANT to). NO ONE would've blamed him really anyway, and add up ALL those facts, the plot is really flimsy.