A new study that examined a wide range of psychiatric behaviors, such as admissions related to psychosis, suicide attempts, emergency room visits, and other indicators of psychiatric illness, found that these “abnormal behaviors” occurred more frequently during this time period.

Psychiatrists at the Indiana University School of Medicine have discovered that suicides tend to increase during a full moon, dispelling a centuries-old belief about the effects of the full moon on people.

Alexander Niculescu, MD, Ph.D., explained that their aim was to investigate the hypothesis that suicides rise during the period surrounding full moons and to determine whether high-risk patients should receive more careful monitoring during those times.

The team led by Niculescu conducted an analysis of suicides reported by the Marion County coroner’s office in Indiana between 2012 and 2016. Their study revealed that deaths by suicide showed a notable increase during the week of the full moon, especially among individuals aged over 55 years. Moreover, they also observed that 3-4 p.m. and the month of September represented peak times for suicides.

The team’s research outcomes have been recently published in the Discover Mental Health journal.

Alexander Niculescu highlighted the significance of the study, stating that it offered crucial insights from both clinical and public health perspectives. He suggested that the findings indicate that high-risk patients may require closer monitoring during the week of the full moon, particularly in the late afternoons and even during the month of September.

Niculescu and his team had previously devised blood biomarker tests for various mental health conditions like anxiety, depression, and post-traumatic stress disorder, as well as pain. In this study, they analyzed blood samples obtained from some of the individuals by the coroner’s office to identify the specific biomarkers present.

Niculescu explained that they assessed a list of the most significant blood biomarkers for suicidality which they had identified in earlier studies. The biomarkers they discovered for suicidality, that are predictive of death by suicide during full moon, peak hour of day, and peak month of the year, were genes that control the body’s internal clock, also known as the ‘circadian clock.’ By analyzing these biomarkers, the team also discovered that individuals with alcohol-use disorder or depression might be at higher risk during these particular time periods.

According to Niculescu, the augmented light emanating from the full moon could be the reason behind the surge in suicides during that period. The natural 24-hour cycle of the human body that regulates our sleep and wakefulness, also known as the circadian rhythm, is significantly influenced by ambient light. Moonlight may be affecting individuals during a time when it should have been darker, leading to the observed impact on suicidal tendencies.

“The effect of ambient light and body clocks in suicide needs to be studied more closely, along with how people sleep and their exposure to light,” Niculescu adds. “Changes in light can affect vulnerable people, in conjunction with other risk factors.”

Regarding the other two periods with high rates of suicide, Niculescu explained that the peak from 3 to 4 p.m. may be attributed to daily stressors and the gradual decrease in ambient light during that time, leading to a lower expression of cortisol and circadian clock genes. On the other hand, September marks the end of summer vacations for many people, which may cause stress. Additionally, the reduction in daylight hours during that season could also contribute to seasonal affective disorder symptoms.

“Our work shows the full moon, fall season and late afternoon,” adds Niculescu, “are temporal windows of increased risk for suicide, particularly in individuals who suffer from depression or alcohol use disorders.”

Niculescu intends to investigate whether exposure to screens at night could potentially contribute to increased suicidality in people, particularly among younger individuals, in the future.

“Some people have a full moon in their hand every night,” Niculescu comments. “It’s an area we absolutely need to study further.”

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