I was grieving for that day of storm,
that day of storm, destined for me,
laid upon me, heavy with tears...
of the storm's floodlike destruction
weighed on me,
and of a sudden on my couch at night,
upon my couch at night no dreams were granted me. 
the loss of dreams heralds the fall of the city and the loss of an empire.
We can only grasp the full power of Ningal's terrible complaint when we understand her vital role, and that of the succession of high priestesses who embodied her, as dreamers and dream interpreters.
In The Treasures of Darkness, Thorkild Jacobsen made a strong case that Ningal, like her mother Ningikuga, was a goddess of reeds as well as of the Moon. For the people of ancient Sumer, reeds defined a liminal environment, between the marshes and the dry land, symbolically a place of passage between states of consciousness and reality.
Betty de Shong Meador writes in her wonderful book Inanna, Lady of Largest Heart: "Ningal wanders in that borderland between dry ground and the watery deep of the rivers or ocean. In that transitional space between solid consciousness and the muddy unconscious, dreams emerge. Ningal is the divine dream-spinner who roams the marsh in the moonlight of her husband and taps the fertile, imaginative play of figures in the darkness that make up dreams."
The high priestess of the Moon god of Ur, Nanna, embodied the goddess Ningal in the annual rites of sacred union in which Nanna was embodied by the king. The hieros gamos was believed to renew the fertility of the land. From day to day, a no less vital function of the high priestess was to receive and pass on to the king and the people "Ningal's gifts of dreams". The phrase comes from the first author known by a personal name in all the world's literature: Enheduanna, poet, princess and high priestess of Nanna at Ur, whose wild and lovely poems evoking the Moon couple's daughter Inanna, Queen of Earth and Heaven, still arouse and unsettle us today.
Scholars parsing the cuneiform texts from Sumer that have survived on baked clay tablets have found extensive evidence that dreams were greatly valued as oracles for both individuals, families and the whole polity. It was believed that the gods expressed their wishes and revealed the future through dreams. Special care was taken in incubating dreams on matters of great importance. The dream seeker would lie down on a special couch - "the shining, fruitful couch" - to seek divine guidance, or seclude herself in a specially constructed reed hut.
In her poem of exile, Enheduanna grieves for a people bereft of the gift of dreams. The poet priestess laments
cannot stretch my hands
from the pure sacred bed
I cannot unravel
Ningal's gifts of dreams
to anyone 
1. trans. Samuel Noah Kramer; in
Thorkild Jacobsen, TheTreasures of Darkness: A History of
Mesopotamian Religion (New Haven: Yale University Press, 1976) 87.
2. trans. Betty De Shong Meador in Inanna, Lady of Largest Heart: Poems of the Sumerian High Priestess Enheduanna (Austin: University of Texas Press, 2001) 66.