For hundreds of years, some have suggested a full moon may cause people to act differently.
Now, psychiatrists at the Indiana University School of Medicine have found that death by suicide increases during the full moon.
“There has been, for a long time, this lore about full moon and exacerbation of mental health issues. We found that suicides are increased during the full moon, particularly in older individuals,” Alexander Niculescu, MD, PhD, author of the study and a professor of psychiatry at Indiana University School of Medicine told Thervaive.
In undertaking the study, the researchers examined data from the Marion Country coroner’s office in Indiana. They looked at data on suicides that occurred between 2012-2016.
They found that suicide deaths increased during the week of the full moon. This increase was found to be greatest among those aged over 55.
They also found that the month of September was a peak time for death by suicide, and the hours of 3pm to 4pm to be the most common time for suicides to occur.
The researchers argue their findings suggest that people who are at high risk of suicide should potentially be more closely monitored during the full moon, during the late afternoons and in the month of September.
In previous research, the same team developed a blood biomarker test for conditions like anxiety, depression and post-traumatic stress disorder.
In this study, they tested blood samples that were previously collected by the coroner to see if certain biomarkers for suicidality were present.
They found that the biomarkers that were predictive of death by suicide during the full moon, during the peak hour of the day (3pm-4pm) and during the peak month (September) were genes that regulate the body’s circadian clock.
They also found that those with depression and alcohol-use disorder may also be at greater risk of suicide during these periods of time.
The researchers say the increased light during the period of the full moon could be what causes an increase in suicide during this period.
Ambient light, like that seen during a full moon, can impact the body’s circadian rhythm. This is the body’s own natural 24 hour cycle that enables the body to regulate periods in which a person is awake or asleep. The increased moonlight during a full moon could be impacting people at a time when it should be dark outside.
“Light can affect so called circadian clock genes, which if activated at a time when they should not be, may affect people’s mood and suicidality. We have shown in the past through blood biomarker studies that circadian clock genes are involved in mood disorders, and suicide. In this new study, we have shown that they are enriched among the biomarkers that are predictive of suicidality during he full moon, as well as other high risk times (late afternoon, month of September),” Niculescu said.
He argues that the effect ambient light can have on the body and in suicide needs to be further studied.
The afternoon peak of suicides between the hours of 3pm to 4pm could be related to stress experienced throughout the day, as well as a reduction in light that begins to occur at that time. This causes lower cortisol as well as a lower expression of circadian clock genes.
The researchers suggest that the peak of suicides in September could be due to people experiencing the end of their summer vacation. They argue this could cause stress along with season affective disorder. They also suggest light may play a role here as well, as daylight begins to decrease during September.
The researchers hope to expand their study to examine the impact exposure of screens during the night can have on suicidality.
“We would like to study the influence of light from screens of electronic devices used at night. Some people, especially younger people, have a full moon in their hand every night, i.e. a cell phone,” Niculescu said.