Biorhythm is an in-game mechanism present in the games Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn that affects all characters on the battlefield. Depending on a character's Biorhythm status, they may receive a bonus or penalty to Hit, Avoid, Skill activation and chance of finding hidden items. Biorhythm status can also be affected by the Bliss and Sorrow chants that Herons can learn, as well as the Matrona staff; also, the skill Tempest doubles biorhythm effects, whereas the skill Serenity halves biorhythm effects.