Like Sleepy this piece of music is a result of a study in the art of keeping syntunes (synchronous or simultaneous melodies) simple. The topic here is late night. For many people, the most convenient time to relax before going to sleep. Here we are witnessing how night enters.
Although the piece is not specifically intended as sleep music, its sleep-inducing effect is perhaps more profound than that of Sleepy. Perhaps because of the hypnotic effect of the bass melody from the 18th bar onward.