Full Moon on Friday the 13th

Full Moon Friday

This sounds pretty ridiculous, right? After all, it’s just a date on the calendar.

These two events happening on the same day may not happen again until 2049, which makes it pretty cool. But do you think it actually makes people crazier? To answer this question we contacted the statisticians at Intermountain McKay-Dee Hospital. Being one of the busiest Emergency Rooms in Utah has allowed them to track data from a very large number of cases, which offers enough information to determine if our findings are “statistically relevant.” However, given the fact we are chasing a superstition, does that really matter?

Before we look at the data, let’s quickly explore these two nearly coincidental superstitions.

Friday the 13th

There is a Hollywood movie about the evil nature of this date; do we need to say more?

Most of the modern world uses the Gregorian calendar. We are comfortable with having 12 months, 52 weeks, and between 28 and 31 days each month, all thanks to this calendar. Given this structure, a Friday the 13th occurs several times each year.

[Side note] Friday the 13th will happen at least once every year, but never more than 3 times.

This date has several historical and biblical events that can be used to validate its bad/evil/unlucky nature. Several studies have shown that billions of dollars are lost in business every time the number 13 comes up on the calendar. This is even stranger because it doesn’t necessarily only happen on Friday the 13th. In fact, the superstition surrounding the number 13 doesn’t stop with the date. There is even a word for this: triskaidekaphobia – the fear of the number 13.

Next time you are staying in a hotel, check to see if there is a 13th floor. Many hotels leave this number out because there are so many people who refuse to stay in a room associated with the number 13. And what about Apollo 13? Did this mission suffer simply because of the number 13?

Full Moon

A full moon happens at least once every month, sometimes even twice (a blue moon). A full moon occurs when the sun, earth, and moon all line up and light from the sun is reflected off an entire hemisphere of the moon. A few scientifically significant things happen when the moon is full, such as a change in ocean and lake tides caused by shifting gravitational forces between the sun and the moon. Could this also cause psychotic behavior in humans? The human body is composed of 50-60 percent water. Can that mean that changes in gravitational pull can cause us to act even crazier than normal?

[Side Note] A blue moon occurs once every 2 to 3 years.

Actually, there are no recorded scientific studies that links lunar cycle and human psychosis, even though thousands of studies have been performed to explore this superstition. Most “evidence” presented on the topic is anecdotal, or includes a very small, statistically irrelevant data sets. If there is no proof, why do we think people act crazier when there is a full moon?

Our Data

We were able to review data from more than 1,000 cases that took place either during a full moon, or on a Friday the 13th. In these cases, there is no statistical increase in patients being treated for psychotic episodes in our emergency room.

Why the superstition?

Each time there is a full moon, or the 13th day of the month falls on a Friday, why do people think things get crazy? When they happen together, is the psychotic effect multiplied? Or could it be that the superstition is just in our head?


What do you think?