OK, let me settle this once and for all:
Anatomy of a glowstick:
There are two parts to a glowstick, 1) a plastic shell, and 2) a glass ampule (vial)
A glow stick contains two sets of chemicals 1) in the plastic shell there is hydrogen peroxide (H2O2) and 2) in the ampule is a phosphorluminescent dye or diphenyl oxalate with different configurations (esters) resulting in different colors.
When the glass is broken, the two sets of chemicals react with each other (duh). Without getting into the various stages of the reaction between H2O2 and the phenyl oxalate, the result is the generation of a photon of energy. The wavelength of the photon is determined basis the dye and/or color of the plastic shell.
Heating up a glowstick will make the reaction go quicker, thus resulting in a brighter glow, but reducing the length of the reaction. This is because there are more photons being generated more quickly.
Cooling a glowstick will make the reaction go slower, thus a duller glow, but longer reaction as there are less photons being generated. It is possible to stop the glowstick reaction entirely; there are some science experiements for kids that show if you use dry ice or put a glowstick in the freezer it is possible to make this happen.
Bottom line:
If you are looking to pour the stuff into another container, becareful as the peroxide will stain/bleach your clothes. If you heat up the glowsticks there will be more light for a shorter period of time, if you cool them there will be less light but for a longer period of time.
Also, it should go without saying, do not put a glowstick in the microwave, the plastic will melt and you will have a large mess to clean up.
Enjoy!
-Ryan