Light emitting diodes, also called LEDs, are solid-state devices that convert small amounts of safe electrical energy into light. They can be switched on and off much faster than incandescent lights, producing the crisp strobe-like pulses most effective at inducing the frequency following response needed to guide the user through the brainwave states. For BrainTap, blue LEDs were chosen for their pure, cool, calming color. Our operational research showed that users preferred the blue effect through closed eyes more than any other LEDs available. It is important to note that a person who is prone to seizures should not use the light portion of the BrainTap headset system.