Nighthawks was probably Hopper's most ambitious essay in capturing the night-time effects of manmade light. For one thing, the diner's plate-glass windows cause far more light to spill out onto the sidewalk and the brownstones on the far side of the street than is true in any of his other paintings. As well, this interior light comes from more than a single lightbulb, with the result that multiple shadows are cast, and some spots are brighter than others as a consequence of being lit from more than one angle. Across the street, the line of shadow caused by the upper edge of the diner window is clearly visible towards the top of the painting. These windows, and the ones below them as well, are partly lit by an unseen streetlight, which projects its own mix of light and shadow. As a final note, the bright interior light causes some of the surfaces within the diner to be reflective. This is clearest in the case of the right-hand edge of the rear window, which reflects a vertical yellow band of interior wall, but fainter reflections can also be made out, in the counter-top, of three of the diner's occupants. None of these reflections would be visible in daylight.Hopper's biographer, Gail Levin, speculates that Hopper may have been inspired by Vincent Van Gogh's Café at Night, which was showing at a gallery in New York in January 1942. The similarity in lighting and themes makes this possible; it is certainly very unlikely that Hopper would have failed to see the exhibition, and as Levin notes, the painting had twice been exhibited in the company of Hopper's own works. Beyond this, there is no evidence that Café at Night exercised an influence on Nighthawks. Although there is no evidence at all (other than the fact that Hopper admired the story), Levin also suggests that he may have been inspired by Ernest Hemingway's 1927 short story, The Killers.