In addition to being a beaming source of entertainment for raves and caves, the light sticks are an excellent item to use in a 72-hr-kit or just as an extra source of light when camping or when the power goes out. They're so great because they don't require batteries or electricity and are waterproof, inexpensive, and easily disposable.
Because light sticks, a.k.a. glow sticks, do not require electricity or batteries they are the safest source of lighting after a natural disaster. (The chemical contents are also non-toxic and non-flammable.) The military even uses light sticks as a light source or light markers.
This source of light for the public typically provides anywhere from 5 hours to 24 hours of light before the glow fades out. The time you get from your light stick should be indicated on the package. Light sticks come in lots of different colors and lengths.
There are some things to know depending on your plans for using light sticks, even though they are very safe. If you are able to freeze your light stick it will prolong the amount of time it glows, however the warmer it is, the brighter it will glow until the chemical reaction runs out. They should be stored in a cold, dry, place, and if you somehow get the chemicals on your clothes, (which would only happen if the plastic casing was punctured, which is very difficult to do), it can stain.
I especially like to use light sticks with children. They are great to have around when the power goes out and your kids need a "nightlight" to help them to not be scared. I have also used them for the same purpose when I go camping. It's surprising how much light they actually produce in a dark room. We recommend keeping light sticks in your home, car, 72-hour kits and shelter in place.