Vairagya is a means for attaining wisdom of the self. It is not the goal itself. A realized sage has neither desire nor dispassion. If you give him a little dry bread, he is quite satisfied, and will not grumble. If you give him the best sweetmeats, milk and fruits, he will not refuse, but he will not be elated by good food. He has equanimity of mind, and is above likes and dislikes. He always delights in his own self only, but not in external objects.
When you go into sleep, you 'lose' all practical knowledge. The moment the mind starts its activity once again, the whole miraculous motion involved in life begins anew.