Whether it's for trick-or-treating on Halloween or ringing in the New Year, glow sticks are a popular item to generate light safely and cheaply. The light in glow sticks is created when the two chemicals inside are "cracked," or mixed, and a natural light is emitted. Once this happens, the light output can't be stopped, and the glow sticks can't be reused ... unless you do this one thing: Freeze them. The cold temperature stops the chemical reaction. Keep the glow sticks in the freezer until frozen solid; when you want to reuse them, just thaw them and re-snap to create the natural glow.