Coast Guard Rules and Regulations
It is first necessary to identify what a federal Coast Guard requirement actually is. The process begins with Congress enacting a law that pertains to marine vessels. Regulations are then created that implement the law in the form of requirements that are defined in the Code of Federal Regulations. The Federal Boat Safety Act of 1971 is an example of a law that was implemented through requirements like tougher lighting standards, that were enforced by the Coast Guard. So theoretically, the Coast Guard doesn't make the boating light requirements, it just enforces them through standard Vessel Safety Checks.
Kayak Lighting Requirements
There are relatively scant Coast Guard requirements for kayak lighting in comparison with other small craft. Unlike most other boats, no lighting is required from dawn to dusk, except in extreme foul weather. At night only a bright flashlight readily available is required, yet having side-running lights as on a sailboat is advised. An excellent resource for the details on proper boat lighting is the Federal Requirements for Recreational Boats brochure--to order, call the Coast Guard Customer info line at 1-800-368-5647.
Visual Distress Signals
This is one other type of light that you are required by the Coast Guard to have aboard in certain areas, even though hopefully you will never have to use it. According to the Coast Guard, "all vessels used on coastal waters, the Great Lakes, territorial seas, and those waters connected directly to them, up to a point where a body of water is less than two miles wide, must be equipped with a Coast Guard-approved visual distress signal." Kayakers don't have to carry day signals, only approved, non-expired night signals. There are two main types of signals, pyrotechnic and an electric distress light. If you choose pyrotechnic signals like red flares, parachute flares or aerial red meteors, the Coast Guard requires that you have at least three on board. The best option is an electronic beacon, as pistol-launched flares must be treated with the utmost caution and are prohibited from use in some states.