One reader was concerned about radiation emissions from electrical gadgets such as the TV and computer. One suggestion is to put a big piece of amethyst on top of the TV, and put a large piece of malachite by the PC.
Draper makes a small screwdriver that can detect electromagnetic radiation. The new televisions and LCD computer screens emit far lower levels of radiation than older products. Keep live mains wires away from the sleeping area, and you can put aluminised plastic film over screen cables, but don't use standard-issue kitchen foil for the purpose.