The irony is that although many of us trade sleep for productivity, we would actually be more productive if we slept more. When we don't get enough sleep, we accumulate "sleep debt" which has to be paid back. (It's no coincidence that we describe this state with a metaphor drawn from banking, one William Wordsworth nicely turned on its head when he asked, in his poem "To Sleep," "Without Thee what is all the morning's wealth?")
The unarguable demands that our bodies make for sleep are a good reminder that we are mere creatures, not the Creator. For it is God and God alone who "neither slumbers nor sleeps." Of course, the Creator has slept, another startling reminder of the radical humility he embraced in becoming incarnate. He took on a body that, like ours, was finite and contingent and needed sleep. To push ourselves to go without sleep is, in some sense, to deny our embodiment, to deny our fragile incarnations—and perhaps to deny the magnanimous poverty and self-emptying that went into his Incarnation.
Please check out the rest of her article: Sleep Therapy. This article was publised in "Books & Culture" in the January/February 2006 edition (p. 7ff).