Laila, Layla, Leïla, Lejla, Laela, Laelah, or Leyla (Arabic: ليلى) is a feminine given name in the Arabic language. The name means "Dusk", the darkest stage of twilight in the evening. Over time it has been taken to mean "Born at Night," "Dark-haired Beauty" or "Dark Beauty." 
The name has long been used in Persian folklore, poetry, and literature. The story of Qays and Layla or Layla and Majnun became a popular romance in medieval Iran, and use of the name spread accordingly; it gained popularity further afield in the Muslim World, among the Arabs, Turkic peoples and in the Balkans and India.
It has also acquired a following in the English-speaking world, especially after the 1970 hit song "Layla" by Derek and the Dominos, the title of which may have been inspired by the medieval romance.
In the Nordic countries, Laila or Lajla (pronounced lie-lah) is derived from the Sami name Láilá, the Sami variant of Helga which means holy.
The name Lailah is the same as the Hebrew word for "night", laylah (לילה). The identification of the word "night" as the name of an angel originates with the interpretation of "Rabbi Yochanan" (possibly Yochanan ben Zakkai, c. 30–90 AD) who read "At night [Abraham] and his servants deployed against them and defeated them” (Genesis 14.14, JPS) as "by [an angel called] night" (Sanhedrin 96a).