No Scientific Evidence Supports an Association Between Moon Phases and Mental Illness
There is no credible scientific evidence supporting an association between lunar phases and mental illness. Multiple well-designed studies have consistently shown no relationship between moon phases and psychiatric presentations or behaviors.
Evidence Against Lunar Effects on Mental Health
Research Studies
- A comprehensive observational analytic cohort study examining 1,857 psychiatric emergency department presentations over 41 consecutive months found no statistical differences in psychiatric presentations across all four lunar phases (new moon, first quarter, full moon, third quarter) 1
- Analysis of 8,473 psychiatric admissions at Naval Medical Center San Diego (1993-2001) revealed no correlation between psychiatric admissions and any phase of the moon, including when broken down by specific diagnoses such as mood disorders or psychotic disorders 2
- A 2019 study evaluating restraints, seclusions, and psychiatric emergencies in a state psychiatric hospital found no significant association between full moon phases and patient behaviors 3
Methodological Considerations
- The JAMA Psychiatry guidelines on evidence for prediction highlight that statistical associations often fail to translate into clinically meaningful predictions 4
- Many beliefs about lunar effects likely represent confirmation bias, where people remember events that confirm pre-existing beliefs while forgetting contradictory instances
- When studies do show associations, they typically fail to control for confounding variables or have methodological limitations
Limited Contradictory Evidence
A few studies have reported potential associations:
- One study found a weak correlation between moon phases and bed occupancy rates and hypnotic medication intake in hospitalized psychiatric patients, suggesting possible sleep disruption effects 5
- An observational study from Australia reported that violent and acute behavioral disturbance was more common during full moon phases (23% of cases vs. approximately 11% expected by chance) 6
However, these findings are outliers compared to the majority of research showing no effect.
Implications for Clinical Practice
Mental health professionals should focus on evidence-based factors known to influence mental health, such as:
- Sleep patterns and circadian rhythms 4
- Social determinants of health
- Medication adherence
- Psychological stressors
- Biological factors
The American Academy of Dermatology guidelines note that mental health conditions like depression and anxiety are associated with medical conditions such as atopic dermatitis, highlighting the importance of addressing physical health to improve mental health outcomes 4
Why the Myth Persists
Despite scientific evidence to the contrary, the belief in lunar effects on mental health remains widespread among healthcare workers, with up to 81% of mental health workers believing in such effects 1. This persistence likely stems from:
- Confirmation bias (remembering events that confirm beliefs)
- Attribution of unusual behaviors to memorable environmental factors
- Cultural and historical traditions linking the moon to madness
- The tendency to notice patterns even when they don't exist statistically
Conclusion
When evaluating factors that influence mental health, clinicians should focus on evidence-based approaches rather than lunar cycles. The scientific consensus, based on multiple well-designed studies, indicates that moon phases have no meaningful impact on psychiatric presentations, admissions, or behaviors.