When standing under streetlights the player is impervious to attacks as the Taken cannot enter well lit areas of the game.
This gives you the opportunity to regenerate health at a faster pace. Another major aspect of the game, connected to his amnesia about ever writing a novel called Departure is finding the manuscripts of the book scattered about the areas of Bright Falls.
Alan Wake reads the events and plot twists in the book and is unable to remember writing it, even though he is aware that it is his own work that he holds in his hands.