Chemiluminescence in glow sticks works by fluorescence. I suspect it may have different mechanisms in living systems, but fluorescence is still common. The principle of fluorescence is that the chemicals emit light at a particular wavelength as a result of the formation of a particular chemical bond, which controls the energy (and thus the wavelength) of the light. The reaction does not otherwise produce a great deal of heat; most of the energy released is in the form of light. Different chemicals have different energy levels, and thus different wavelengths and reaction times, and thus lifespan. Biological systems have a similar range of options when producing light.

The chemicals that make up some glow sticks are toxic, which means that they can be bad for the environment if they escape the plastic casing of the glow stick.