Sleeplessness and the incapacity for leisure are really related to one another in a special sense, and a man at leisure is not unlike a man asleep. …Or as the Book of Job says, “God giveth songs in the night” (Job xxxv, 10). Moreover, it has always been a pious belief that God sends good gifts and blessings in sleep. …It is in these silent and receptive moments that the soul of man is sometimes visisted by an awareness of what holds the world together … only for a moment perhaps, and the lightning vision of his intuition has to be recaptured and rediscovered in hard work. (41-42)
From Leisure: the Basis of Culture by Josef Pieper (1952).
And I am reminded of this poem by Czeslaw Milosz:
I looked out the window at dawn and saw a young apple tree
translucent in brightness.
And when I looked out at dawn once again, an apple tree laden with
fruit stood there.
Many years had probably gone by but I remember nothing of what
happened in my sleep.