Mistaking sleepiness for style, there are certain jazz singers who would best be marketed on the labels of Ambien prescriptions. Diane Reeves will never know such a fate. Peppered with scatting, legato slides and excursions from form, Diane Reeves’ phrasing is as if someone put little firecrackers all along the melody. With a husky tone inspired by Sarah Vaughan yet propelled by a wildly imaginative, multiple-octave vocal range, the jazz singer’s interpretations often reach for—and crack—the stratosphere of syncopation. Reeves’ latest, When You Know, mixes well-chosen pop songs (“Just My Imagination,” “Lovin’ You,” “Windmills of Your Mind”) with lesser-known standards (the incredible “Midnight Sun”). She appears Friday, Oct. 1, at the Napa Valley Opera House. 1030 Main St., Napa. 8pm. $40–$45. 707.226.7372.