Dust never sleeps

Or, when it does, the ultraviolet wakes it up.

On the Moon, and presumably any airless body, UV-stimulated emission and re-capture of electrons in the cavities left between dust grains can charge the dust, and the negatively charged particles can be levitated by electrostatic repulsion.

We have recorded micron-sized insulating dust particles jumping to several centimeters high with an initial speed of ~0.6 m/s under ultraviolet illumination or exposure to plasmas, resulting in an equivalent height of ~0.11 m on the lunar surface that is comparable to the height of the so-called lunar horizon glow.

Since there's no reason it should jump straight up, a particle will fall down again some distance from its original location. So dust will spread.

This is only significant in airless regions, so don't blame the state of the bookcase on UV light.