I sleep, but my heart waketh: it is the voice of my beloved that knocketh, saying, Open to me, my sister, my love, my dove, my undefiled: for my head is filled with dew, and my locks with the drops of the night. I sleep, but my heart waketh - This is a new part; and some suppose that the fifth day's solemnity begins here. Though I sleep, yet so impressed is may heart with the excellences of my beloved, that my imagination presents him to me in the most pleasing dreams throughout the night. I doubt whether the whole, from this verse to the end of the seventh, be not a dream: several parts of it bear this resemblance; and I confess there are some parts of it, such as her hesitating to rise, his sudden disappearance, etc., which would be of easier solution on this supposition. Or part of the transactions mentioned might be the effects of the dream she had, as rising up suddenly, and going out into the street, meeting with the watchmen, etc., before she was well awake. And her being in so much disorder and dishabille might have induced them to treat her as a suspiciovs person, or one of questionable character. But it is most likely the whole was a dream.
For my head is filled with dew - She supposed he had come in the night, and was standing without, wet, and exposed to the inclemency of the weather.