Sticks in the hot bath give off much more light than those in room temperature baths. Sticks in cold baths give off the least light. The rates of chemical reactions usually increase with temperature. The rates of all simple, single step chemical reactions increase with temperature. Chemiluminescence is a phenomenon wherein chemical molecules produced in a chemical reaction are produced in a chemically excited state that releases light energy.
Fireflies are among the creatures that emit light at ordinary temperatures.
Light sticks are based upon the same sorts of chemical reactions as take place in fireflies. In one of the formulations for light sticks, hydrogen peroxide is stored in a thin glass ampoule. The carbon dioxide is thought to be produced from an excited dimer. This dimer transfers its energy to a dye. The dye fluoresces, and this light is what one perceives.