John Field is credited as the true 'inventor' of the Nocturne. After experimenting with other names such as Pastorale, Serenade, and Romance, he settled on “Nocturne” when his first one was published in 1812.
Field’s Nocturnes follow no known form, nor do they develop a given theme. Instead, they set up a mood and atmosphere of tenderness and dreaminess combined with a continuous flow of beautiful melody that appealsdirectly to the listener's willingness to share an emotion, mostly of consoled sadness.
It was Field's Nocturnes that greatly influenced Chopin, who absorbed the emotional characteristics of the Nocturne style and used them to create his own unique expressive compositions.