What are the themes in the film Insomnia?

I think that one of the themes that emerges in Nolan's
film is the complexity of characters.  The depiction of characters who depict multiple
layers to them becomes one of the critical elements in the film, and also representative
of Nolan's work.  Dormer possesses many layers to his character, reflecting a level of
torment that is common in Nolan's work.  The great crime fighter contains a level of
guilt and transgression that makes him uniquely different from those around him.  Dormer
becomes this figure by the end of the film.  At the same time, Burr is faced with
constant choices that will end up defining her own reality and her identity.  One of
them is present at the end of the film when she is prepared to bury the casing evidence
that would prove Dormer's guilt.  Her willingness to do this in loyalty to Dormer, but
then her embrace of the "right path," thought it might cause damage to Dormer is another
representation of the the theme that individuals have freedom and autonomy, but must
also act in a manner whereby happiness is not the direct result of such action.  This is
another theme in the film that is brought out through the arc of character
development.