How Does a Full Moon Affect People’s Behavior and Emotions?

There is no solid scientific evidence that a full moon affects human behavior, though the belief is common.

Belief

The idea of “lunar effect” is old (lunacy comes from Luna).

Evidence

Reviews of many studies found no link between full moons and crime, ER visits, births or mental health.

Sleep

One 2013 study found people sleep about 20 minutes less near a full moon, but later studies disagreed.

Why it persists

Confirmation bias.

Fact

The full moon does affect tides.

What studies found

The “lunar effect,” a belief that the full moon changes behavior, has been tested many times. A 1996 meta-analysis in Psychological Reports by Rotton and Kelly of 37 studies found no relationship between lunar phases and human behavior, including crime, psychiatric admissions and births. Later reviews reached similar conclusions.

• A 2013 study in Current Biology by Cajochen at the University of Basel found participants slept about 20 minutes less and had lower melatonin around the full moon in a lab setting, but follow-up studies have not consistently replicated this.
• A 2014 analysis of 12,000 children across 5 continents found children slept about 5 minutes less near full moon.
• Moonlight can disturb sleep for people sleeping outdoors or with bright windows.

Why belief persists

Confirmation bias drives it. People notice odd events during full moons and forget those at other times. The word “lunatic” derives from Latin luna. The Moon does cause ocean tides through gravity, but the human body is far too small for similar tidal effects.

What studies found

A 2014 meta analysis of 37 studies found no consistent link between the lunar cycle and human behavior or births. Studies of emergency room visits and psychiatric admissions show no clear effect. Some studies suggest small sleep changes around full moon.

Why belief persists

Confirmation bias and cultural stories keep the idea alive. The word lunatic comes from the Latin luna.

Studies of births and emergencies

A 2005 Cochrane review of 21 studies found no effect of the lunar cycle on births. A Dutch study of 2,500 patients found no relation to psychiatric admissions. Some research shows people sleep about 20 minutes less near full moon, in a 2013 Current Biology study in a lab, though not confirmed in larger datasets. The moon’s tidal effect on a human body is too weak to matter.

Why it feels true

Illusory correlation makes people remember busy nights during a full moon. Nurses and police often report this, but data from emergency departments do not support it. The Latin word luna is the root of lunacy, from old beliefs.

Based on data from the Cochrane Library and Current Biology