How does the full moon actually affect human behaviour?
The belief that the full moon influences mood, sleep, crime, and birth rates is ancient and widespread. Researchers have tested these claims in studies and meta-analyses across psychiatry, emergency medicine, and sleep science.
2 established, 1 disputed, 3 debunked, 1 unresolved. We do not pick an answer; the evidence places each claim. How we decide
12 citations from 6 independent sources - 6 echo the same voices and count once. Graded B1-D1.
Added 3 Jul 2026 - updated 9 Jul 2026
What the four states mean
- Establishedsupported, uncontested
- Disputedcredible sources disagree
- Debunkedrefuted by the evidence
- Unresolvedno settled answer
Established 2supported, uncontested
Meta-analyses of many studies find no reliable association between the full moon and aggregate human behaviour such as crime, psychiatric admissions, suicides, or crisis-call volume.▰▰▱▱▱ likely1 source
Supports- A 1985 meta-analysis by Rotton and Kelly pooling dozens of studies found full moons unrelated to crimes, suicides, psychiatric problems, and crisis-centre calls.Lunacy and the Full Moon - Scientific American analysis
Many healthcare workers, police, and members of the public believe the full moon increases erratic behaviour and workload.▰▰▱▱▱ likelysummary-sourced1 source
Supports- Surveys of emergency and mental-health staff repeatedly find large proportions believe full moons bring busier or more chaotic shifts despite the lack of supporting data.Lunar effect - Wikipedia summary
Disputed 1credible sources disagree
The lunar cycle measurably affects human sleep.▰▰▰▱▱ roughly even chance1 against2 points
Supports- A 2013 sleep-lab study reported that around the full moon deep sleep fell about 30 percent and participants took longer to fall asleep and slept around 20 minutes less.Evidence that the Lunar Cycle Influences Human Sleep - Current Biology (2013) primary
Against- A 2014 reanalysis of three large EEG datasets failed to replicate any lunar effect on sleep and suggested earlier results reflected publication bias.Lunar cycle effects on sleep and the file drawer problem - Current Biology (2014) primary
Debunked 3refuted by the evidence
The 'lunar effect' - that a full moon drives up violent crime, psychiatric emergencies, and emergency-room visits - is supported by the data.Refuted by
Surveys show many police officers and hospital staff still report perceiving more incidents around the full moon, and a few individual studies report small associations.
refuted1 againstsummary-sourced2 pointsThe claim rested on- Reviews and emergency-department studies generally find no increase in patient volume, psychiatric visits, or violent incidents on full-moon nights.Lunar effect - Wikipedia summary
Refuted by- Surveys show many police officers and hospital staff still report perceiving more incidents around the full moon, and a few individual studies report small associations.Does the Moon Affect Humans? - Cleveland Clinic summary
Human birth rates rise around the full moon.Refuted by
The belief persists among some clinicians and in folklore, and a few small studies have reported apparent peaks.
refuted1 againstsummary-sourced2 pointsThe claim rested on- Large analyses of millions of births have found no correlation between lunar phase and the timing or number of deliveries.Lunar effect - Wikipedia summary
Refuted by- The belief persists among some clinicians and in folklore, and a few small studies have reported apparent peaks.Does the Moon Affect Humans? - Cleveland Clinic summary
The moon's gravity exerts meaningful 'biological tides' on the human body because the body is mostly water.Refuted by
Proponents argue that because the body is largely water, lunar gravity should affect it as it affects the ocean tides.
refuted1 against2 pointsThe claim rested on- Physicists note the moon's tidal force on a person is negligible; only large open bodies of water produce tides, and a nearby object exerts a stronger pull than the moon.Lunacy and the Full Moon - Scientific American analysis
Refuted by- Proponents argue that because the body is largely water, lunar gravity should affect it as it affects the ocean tides.Does the Moon Affect Humans? - Cleveland Clinic summary
Unresolved 1no settled answer
If any genuine lunar influence on human sleep exists, increased natural light around the full moon - rather than gravity - is the leading candidate explanation, but this remains unconfirmed.▰▰▰▱▱ roughly even chance1 against2 points
Supports- A 2021 field study found people in communities with little electric light fell asleep later and slept less in the nights before a full moon, consistent with a moonlight cue.Moonstruck sleep: synchronization of human sleep with the moon cycle - Science Advances (2021) primary
Against- Other large studies found no lunar effect on sleep, so whether any real influence exists, and through what mechanism, is still open.Lunar cycle effects on sleep and the file drawer problem - Current Biology (2014) primary
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