For a supposed nocturne, Heavy Sleep is dense, dramatic, and packed with activity.
The material of the piece is set on a repeating ground of chromatic scales, an idea taken from the coda of Chopin’s Op. 48 no. 2 nocturne. The piece’s character, though, is based more on Op. 48 no. 1, its measured pacing belying the terrors of its middle section.
Heavy Sleep begins with isolated chords—seemingly disconnected events which gradually reveal an overall direction as they increase in complexity and volume. Eventually the music gets “stuck” on a repeated whole-step interval—not much in terms of a theme, but revealed in greater relief by the variety of things happening around it. After a loud confrontation between the whole-step and the opening chords, the music evaporates in a harmonic haze, turning the same idea over and over.