Cyalume light sticks are a neat little invention that have been around for a long time. They work quite simply by gently breaking the outer casing to release and mix liquids that somehow produce light. Anyway, the idea is simple and time-tested.
Light sticks are usually rated to last for several hours or more, are lightweight, and safe for children to handle. Unfortunately, that’s where the pros end. Most light sticks sold for emergency use produce very low levels of light (you can’t light up a room with one), they cannot be turned off once the chemicals have been mixed, have a limited shelf life (they tend to expire after a few years), and have been found to be susceptible to extreme cold temperatures. Light sticks can be purchased that produce much more light but only last for a few minutes up to 30 minutes.
Regardless of the downsides, I still choose to keep a few around for two reasons: (1) they are still useful enough as an last-ditch emergency light source, (2) I believe in redundancy, (3) kids love them. Therefore, light sticks are yet another option in my arsenal of lights. If you can grab some for a good price, stash a few in your bug out bag and vehicle kits and don’t think about them again for a few years.