The patriarch of Mahabharata Bhishma is supposed to have told the Visnusahasranama stotra to Yudhisthira from his bed of arrows in the presence of Sri Krishna. This has come down to us from ages. Repetition of God's name has great power. Sanatana Dhama with its roots in the Veda has given nama-japa a very high place in the practice of religion.
The distinctive feature of Visnu sahasranama is that it emphasizes that the object of adoration is the Supreme Deity, the Light that lights up all existence. The superiority of chanting the Lord's name is that it causes no harm to others, does not need any one's services, requires nothing, not even a leaf or a flower, and is not dependent on suitable time or place.
The chanting can be done at any time. The book gives interpretation of the Sanskrit shlokas in English.