The arrangement has several light sources, of which each radiates electromagnetic waves in a narrowband wavelength range, whereby the ranges preferably do not overlap, and a control unit for controlling the light sources so that a calming or stimulating ef...

The coaxial detachable housing sections (5,6) have opposing edges, so that projections extending in axial direction from the edges, engage in corresponding recesses of the housing sections. The projections have retaining noses (14,15) protruding in transve...