Suicides skyrocket when there’s a full moon — Scientists finally think they know why

INDIANAPOLIS — Full moons have always had a connection to strange and mysterious events which people can’t explain. Unfortunately, the rise of a full moon also has a link to a rise in deaths by suicide. Now, scientists say they may be able to explain why rates of suicide skyrocket during the week of a full moon.

Researchers from Indiana University School of Medicine discovered specific blood markers in the bodies of people who took their own lives that changed due to the rising of a full moon.

“We wanted to analyze the hypothesis that suicides are increased during the period around full moons and determine if high-risk patients should be followed more closely during those times,” says Alexander Niculescu, MD, PhD, in a university release.

Niculescu and the team examined data from the Marion County coroner’s office in Indiana, specifically tracking suicides taking place between 2012 and 2016. Those records revealed that suicides significantly increase at three separate times: during the week of a full moon, between the hours of 3 p.m. and 4 p.m., and in the month of September. People over the age of 55 were also more likely to commit suicide.

“From a clinical perspective and a public health perspective, we found some important take-home messages in this study,” Niculescu continues. “High-risk patients should possibly be followed more closely the week of the full moon, during late afternoons and perhaps the month of September.”

A full moon can throw off a person’s body clock

Niculescu’s team previously developed a blood biomarker test to detect mental health conditions such as anxiety, depression, and PTSD. Using blood samples from bodies in the coroner’s office, the team was able to look for similar markers at their time of death. They discovered that victims of suicide had signs that their “internal clock” was not functioning right at the time of their death.

“We tested a list of top blood biomarkers for suicidality that we identified in previous studies,” Niculescu reports. “The biomarkers for suicidality that are predictive of death by suicide during full moon, peak hour of day and peak month of the year compared to outside of those periods appear to be genes that regulate the body’s own internal clock, so called ‘circadian clock’. Using the biomarkers, we also found people with alcohol-use disorder or depression may be at higher risk during these time periods.”

Study authors suggest that the added light from a full moon could be causing the increases in suicides during these weeks. Ambient light can have a major impact on a person’s circadian rhythms — the natural 24-hour clock the body follows to regulate our sleep/wake cycles. Simply put, moonlight may be disrupting certain people who are expecting the sky to be darker.

“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 continues. “Changes in light can affect vulnerable people, in conjunction with other risk factors.”

Why is September a major suicide month?

As for the other two major periods for suicide risk, researchers say suicides from 3 p.m. to 4 p.m. could be a result of stressors building up throughout the day. There is also a decrease in light from the beginning of the day that may be affecting a person’s circadian clock genes.

As for suicides in September, study authors say many people could be experiencing a letdown at the end of summer, causing them stress. This time of year can also trigger seasonal affective disorder, as daylight decreases after summer.

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

The researcher adds that scientists also need to look at the impact of screen time on suicide risk. The light from these digital devices can also affect circadian rhythms.

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

The findings are published in the journal Discover Mental Health.

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