How we cite our quotes:
The sight seemed to paralyse me […] (4.62)
The very sight of Dracula's face, even as he's sleeping (or whatever it is vampires do) is enough to "paralyse" Jonathan.
Then, too, Lucy, although she is so well, has lately taken to her old habit of walking in her sleep. (6.39)
Lucy's habit of sleepwalking makes her vulnerable to Dracula – it puts her in a state of semi-conscious passivity.
Lucy has not walked much in her sleep the last week, but there is an odd concentration about her which I do not understand; even in her sleep she seems to be watching me. She tries the door, and finding it locked, goes about the room searching for the key. (6.41)
Lucy's passivity while she's sleepwalking makes her easy to Dracula to control.