<h4>Introduction</h4>The potential connection between lunar phases and human activities has fascinated scientists, medical professionals, and the general public. The present study evaluates the possible association between the moon phases and admissions to a major regional trauma hospital.<h4>Methods</h4>All patients admitted to the trauma emergency department from 2018 to 2024 were retrieved. The Astronomical Applications Department of the U.S. Navy website was accessed to retrieve data on the lunar cycle phases. A multiple linear model regression analysis using the Pearson Product-Moment Correlation Coefficient (r) was used to assess the association between the number of patients admitted to the emergency trauma department and the percentage of the moon illuminated.<h4>Results</h4>Data were collected from 53,594 patients (mean age was 36.0 ± 25.4 years); 45.4% (24,337 of 53,594) were women. There was no evidence of an association between the number of patients admitted to the trauma emergency department and moon phases (P = 0.1).<h4>Conclusion</h4>There is no statistically significant association between moon phases and the frequency of visits to the trauma emergency department. Methods All patients admitted to the trauma emergency department from 2018 to 2024 were retrieved. The Astronomical Applications Department of the U.S. Navy website was accessed to retrieve data on the lunar cycle phases. A multiple linear model regression analysis using the Pearson Product-Moment Correlation Coefficient ( r ) was used to assess the association between the number of patients admitted to the emergency trauma department and the percentage of the moon illuminated. Results Data were collected from 53,594 patients (mean age was 36.0 ± 25.4 years); 45.4% (24,337 of 53,594) were women. Introduction The potential connection between lunar phases and human activities has fascinated scientists, medical professionals, and the broad community for ages [ 1 , 2 ]. The idea of the moon’s effect on human behaviour, the"lunar effect", dates back to primitive societies [ 3 , 4 ]. Ancient cultures often correlated the moon’s phases to some human events and health issues. They hypothesised an association given the visible effects of the moon on natural phenomena (such as tides); for this reason, they believed that comparable influences might occur within the human body [ 5 – 7 ]. Over the years, this hypothesis has grown, and most recent studies have tried to analytically examine the association between lunar phases and various aspects of human activity, such as crime rates, frequency of births, psychiatric disorders, and other events [ 3 , 8 , 9 ]. Lately, lunar phases, particularly the full moon, have been related to different occurrences, such as rising emergency department (ED) access, hospital admissions, and patient symptoms [ 1 , 10 , 11 ], with controversial findings [ 12 – 24 ]. An increased frequency of crimes and psychiatry admissions related to the moon cycle has been reported [ 2 , 25 ]. For the databases of the German institutions, the OPS (operation and procedure codes) reported in Appendix 1 were used in combination with the ICD (International Statistical Classification of Diseases and Related Health Problems) codes, also noted in the appendix. Data collection All patients admitted to the trauma ER from 2018 to 2024 were retrieved. The following data were retrieved: the number of patients admitted, the date of admission, and the age and gender of admitted patients. The Astronomical Applications Department of the U.S. Navy website [ 38 ] was accessed to retrieve data on the lunar cycle phases. The red trend line expresses the association between the two variables, with a steeper slope indicating a stronger relationship Discussion The current study indicates no statistically significant association between the moon phases and the frequency of admissions to the trauma emergency department. Throughout the centuries, lunar phases have captivated humanity, influencing beliefs, traditions, and, according to some, even health [ 3 , 39 , 40 ]. Myths and legends from various cultures speak of the moon’s influence on our well-being, tracing a delicate thread between the lunar cycle and human health [ 41 – 43 ]. In ancient Rome, individuals afflicted by illnesses and disorders would visit sanctuaries dedicated to Diana, hoping to receive her grace and healing power [ 44 , 45 ]. The full moon’s light was believed to purify and invigorate the body and spirit, bringing relief and healing to those in need. Hippocrates’s humoral theory of health, postulated in the fifth century BC, shows that lunar phases influence the balance of bodily humours [ 46 – 48 ]. The full moon increased blood flow, the waning moon facilitated detoxification, the waxing moon promoted tissue regeneration, and the new moon heightened In traditional Chinese medicine, the moon phase is believed to influence various health aspects significantly. It is thought that body fluids, such as blood and Qi, are affected by the moon’s gravitational pull, leading to changes in circulation and fluid dynamics within the body. The full moon represents the peak of Yang energy, while the new moon represents the peak of Yin energy [ 49 , 50 ]. In recent years, efforts to explore the potential link between lunar phases and emergency room visits have gained momentum [ 12 , 40 , 42 , 51 ]. These findings contribute valuable evidence to emergency medicine by dispelling a persistent myth while providing data-driven insights that can help optimise hospital resource planning based on actual trends rather than unfounded lunar cycle assumptions. This study has multiple limitations. It is a retrospective, single-centre study conducted over a limited period. Additionally, the patients’ comorbidities were not taken into account. Common limitations in all medical record review studies include the potential for spurious, incomplete or conflicting data.