Chasidut zu Zechariah 4:78

Therefore, before washing the hands in the morning, it is forbidden to touch the 7 openings in the head - the two eyes, two nostrils, the mouth and the two ears (Shulchan Aruch Siman 4 Seif 3). These seven openings are the aspect of da'at, as Rabbeinu z"l brought in a different place (Likutei Moharan 21). These 7 orifices of the head are the aspect of (Zechariah 4:10) "these, sevenfold; the eyes of the Lord are roving to and fro throughout all the earth". This corresponds to da'at and divine providence. Therefore it is forbidden to touch them with the hands prior to washing, in order to not blemish the holy knowledge of the aspect of divine providence through the impurity the knowledge of the natural sciences which take hold of the hands during sleep, as explained above. Therefore the essence of the power of the knowledge of nature which relies solely on the arrangement of the constellations in the sky is at night. It is thus called 'star-gazing', because natural science corresponds to night and darkness. For the essence of light is solely the divine providence of Hashem Yisbarach, as explained above.