Sonmi451 is the project of Bernard Zwijzen, from Hasselt, Belgium and while the name is taken from a novel (David Mitchell’s novel “Cloud Atlas” another reference seems obvious, Shuttle358 but I don't know to which extent as it is the first time I listen to his music.
"Ruis" follows the Slaapwell roadmap in making music which will put listeners asleep. It's a 32 minutes piece of pulsating drone waves slowly oscillating, while a pattern of crystalline piano notes is repeated ad infinitum with a few other elements, in the background.
It is pleasant but highly monotonous and rapidly more soporific than hypnotic. It starts very nicely but next there are almost no perceptible changes of mood, textures or emotions. At least, it totally fits with the concept of Slapwell but the total length seems to be arbitrary as it could last 10 or 60 minutes too. There are subtle variations in the background but not enough to keep you alert and awake.