A most rewarding and fulfilling part of a Muslim’s worship are those blessed moments that he spends praying in the depth of the night, privately addressing his Great Lord, sincerely glorifying Him, humbly imploring Him - beseeching His forgiveness and asking Him for favors. The voluntary "night prayer", or qiyaam, is indispensable for a person’s moral, spiritual, and physical welfare. Yet, it is greatly misunderstood and largely neglected by most Muslims

[From https://islamhouse.com/en/books/51799]