Therefore, Ellen must, "keep [the vampire, Count Orlock] with her until the cock crows," at which time he burns away in the bright beams of the morning sun. .
This same phenomenon, and relation of vampires being restricted to night, carries on through Vampyr and Dracula. In Vampyr, a vampire is described as "The Prince of Darkness," and their weakness to daylight being inferred by character dialogue such as the Lords" remark to the Sister that "[Leone] must not die! She must live "til sunrise". In Dracula this is shown through Van Helsing's remarks that "Dracula has powers only from sunrise to sunset," and that Renfield should be watched, "especially at night".
With this concept of concrete division between night and day creating an "unbreakable rule" firmly planted within the story, and the manufactured associations of that darkness (night) to a vampire's evil, other examples of light and dark could be used to achieve the same mental associations. In these three movies, shadows are also designed to be associated with these ascribed feelings of darkness. In Nosferatu, as stated in the movie's text, daylight frees Hutter from the "shadows of the night," but with its inevitable return, "the empty castle [comes] alive again with menacing shadows". These shadows now associated as something menacing to be freed from, work to retain meaning as those from the realm of the vampire (night).
This association is taken one step further when the shadows become intertwined with the image of the vampire, such as the scene in Nosferatu, in which Hutter is being attacked by Orlock. We are treated to shot that could be best described as the P.O.V. of Orlock as he closes in on Hutter. We see the shadow of Orlock, hands raised, move slowly up Hutter's body and onward to the wall above. This is also even more apparent later in the film when Orlock is ascending the stairs to Ellen's room. The tall shadow of Orlock that is cast upon the wall is massive and looming, not only firmly associating it with, by representing, the vampire, but also symbolizing Orlock's heightened power through the sheer scale of the shadow.