Extract from Shrimad Bhagawat Gita

Chapter-2 Text-69
yo nisha sarvabhootanam tasyam jagarti sanyami
yasyam jagrati bhootani sa nisha pashyato muneh.
Translation: -
That which is night for all the (worldly) beings, a self controlled person remains awake in that and when all other beings are awake it is night for an introspective sage.
Purport:-
In the present shloka(Verse) Lord Krishna tells the difference between a worldly man and a self controlled person. Telling how a person engaged in worldliness is aversed to God he says that he is attached to the Maya (illusions) of the world, material possessions and persons that he remains asleep for the ultimate truth. His attention does not go towards spiritually important issues like true knowledge his deeds, their out come& his end etc. He remain unconsious towards such things as if he is asleep. Whereas a self-controlled person (Who has made himself introverted by controlling his senses and mind) remains fully aware of all these. A materialistic person is engaged in luxury, comfort and making a store of things. Inspite of being equipped with power of reason and logic, he spends his life like birds and beasts and his precious human life which was his means to liberate him from the cycle of life and death goes in vain. Such a person misuses his intelligence to enjoy luxuries and to amass things that even though a thing is not likely to be useful to him he would make a store of it preventing others from using it. Contrary to this, a self controlled person remains unattached to enjoyment and collection. His only aim is God. To know the Ultimate Truth is his being awake at night.
A materialestic person uses his power of intellect cautiously to earn wealth, praise and fame. He keeps an account of even a single penny, a square-inch peice of land; thinks only of what to do to earn fame, this is the consciousness of such a person while a sage a seer who knows the truth behind world and God considers all these transcient things as clay. All this is full of darkness (ignorance) of night and he remains asleep (aversed or indifferent to) such things. For a liberated, and learned devotee there is no world before he reaches Brahma Loka (the abode of God). He sees the reality of world by separating himself from it. As a person amassing wealth does not know what it means to renounce wealth but a person who has renounced it knows about both amassing and renouncing wealth. As a boy has seen only childhood but an old person knows about childhood as well as youth likewise detaching themselves from world and engaging in contemplations the sages realize that the world is transcient (nothing is stable or permanent) and so they become dispassionate and go ahead to reach their ultimate Goal.