During sleep the soul is free to respond to God.

Since souls are permanent, their existence was a fact long before your own life began. Because spiritual life begins before human life, the spirit has its own sphere of activity and independence of sorts, one could say. When you sleep, for example, you are not consciously trying to do things and think things which would enhance your soul's development. You may be essentially unconscious, but your soul is active; your soul is growing. Your soul is drawn to God's light as a flower is drawn to sunlight.

For many, spiritual growth is easier for the soul when the body is asleep, for there are many whose lives are conducted in ways directly opposed to the wishes of God. Those lives can serve as inhibitors to the growth of their respective souls. And therefore, in a period of rest or sleep when individuals are not in control of all that goes on around them, the soul becomes freed to respond to God's light. This is not a metaphor. It is precisely what happens.