Full Moons Cause Madness

Why the Lunar Cycle Is Linked to Emotional Instability and Mental Disturbance

Details

The belief that full moons cause madness, aggression, or emotional instability is one of the oldest and most persistent superstitions related to celestial bodies. The term “lunacy” originates from the Latin word luna, meaning moon, reflecting the idea that the full moon’s light or gravitational pull could disrupt the human mind. Reports of strange behavior, mental disturbances, or increases in crime and hospital admissions during full moons continue to shape public perception—even in the absence of scientific support.

This belief likely emerged from observational coincidences during pre-scientific times, when erratic behavior or nighttime events were often attributed to celestial influences. The full moon, being visually striking and associated with nighttime activity, became a prime suspect in cases of unexplained mental or emotional episodes. As urban lighting was historically minimal, the full moon’s brightness may have contributed to increased activity or sleep disturbances, reinforcing these associations.

Historical Context

This celestial superstition has ancient roots in Roman mythology, where Luna, the moon goddess, was thought to induce periodic insanity. Hippocrates, the father of Western medicine, wrote in the 5th century BCE that “one who is seized with terror, fright and madness during the night is being visited by the goddess of the moon.” Throughout the Middle Ages, mental illness was closely associated with lunar phases, with “lunatics” thought to be more disturbed during the full moon.

Modern Relevance

Despite numerous scientific studies finding no significant correlation between full moons and human behavior, belief in “the lunar effect” remains widespread. Many emergency room staff, police departments, and psychiatric facilities still informally report increased activity during full moons. A 2011 survey of nursing staff found that 81% believed patient behavior was affected by lunar phases. The superstition maintains such a hold that it continues to influence perceptions in medical and law enforcement settings.

Sources

Rotton, J., & Kelly, I. W. (1985). “Much ado about the full moon: A meta-analysis of lunar-lunacy research.” Psychological Bulletin, 97(2), 286–306.
Raison, C. L., & Klein, H. M. (2005). “The moon and madness reconsidered.” Journal of Affective Disorders, 85(1–2), 1–4.