An excerpt from Likutey Halakhos
The reason why we remain awake on Shavuos night is in order to overcome and break the power of sleep, which is an aspect of Targum [Aramaic, which is the language closest to Hebrew. The kabbalists draw a correspondence between Targum/Aramaic and the “Klipas Nogah,” or “Glowing Husk,” which is a mixture of good and evil, and stands between the realms of the holy and the unholy]. We must subjugate its evil element and elevate the good it contains to the Holy Tongue. Indeed, this brings perfection to the Holy Tongue. By so doing, we merit to attain Shemiras HaBris [a euphemism for the transformation of the sexual urge to holiness] and to receive the Torah anew. This is the paradigm of receiving the Torah on Shavuos. Therefore, it is customary on Shavuos to sing “Akdamus,” which was composed in Aramaic. Similarly, on the second day of Shavuos, prior to the reading of the Haftorah, we sing “Yatziv Pisgam,” which also was written in Aramaic. All this is related to our elevation of the good within the Targum to the Holy Tongue (Otzar HaYirah, “Pesach-Sefirah-Shavuos,” sec. 86).