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Lunacy! The Full Moon Affects Motorcycle Safety

Toronto, Ontario, Canada

Lunacy is a factor in motorcycle rider safety! Even the smallest distraction points to danger: the full moon, gracing the sky with its brightness around 12 times a year, and the dazzling supermoon, which comes into focus around once a year, are linked to motorcycle accidents.

Published in The BMJ (British Medical Journal), the research was a joint effort between Princeton University and the University of Toronto and aimed to determine if there was a relation between motorcycle rider fatalities and the presence of a full moon.

Conquer the Moon (Credit: Egan Jimenez Princeton University)

Conquer the Moon (Credit: Egan Jimenez Princeton University)

The full moon or supermoon is an influencer in motorcycle fatalities

Simply put, the researchers aimed to determine if the full moon or supermoon could be an influencer in motorcycle related fatalities. The US based study, used all of the available data the Highway Traffic Safety Administration's Fatality Analysis Reporting System data which has records of fatal vehicular crashes on public roads spanning back to 1975. The researchers collected motorcycle fatality data and used verified data to determine that there were 494 nights with a full moon and 65 nights with a supermoon form 1975 to 2014.

Non-full moon nights a week before and after the full moon were used as control

They related the full moon data to the rider fatality data with the standard statistical tests we all know and love, binomial test, stratified analyses and hierarchical analyses and sensitivity tests too.

Non-full moon nights a week before and after the full moon were used as control. Statistically, control is used as means of comparison to ensure there is less possibility of influencing variables. The important thing to note is that the binomial test was significant, meaning the data comparisons were statistically valid.

40 years of data show motorcycle fatalities increased when there was a full moon

The study concluded that after analyzing 40 years of data, motorcycle fatalities were more common when there was a full moon. Overall, there were 4,994 fatal crashes on nights with a full moon. On control nights without a full moon, there were 8.64 fatal crashes per night. On the nights with a full moon, there were 9.10 fatal crashes. The figures get more alarming when you look at the supermoon data. On the supermoon nights there were 10.82 fatal crashes per night. This means that for every two supermoons there were two more deaths. The study does cite that there are other factors that could influence this result, some related to sensitivities in data or selection but some could be weather, reporting methods or just chance.

Figure1: Cumulative count of bike fatalities on full moon nights compared with control nights

Figure1: Cumulative count of bike fatalities on full moon nights compared with control nights

There is mention of the full moon grabbing the rider's attention being an influencer and I was quick to brush this off, but after a second thought, I recalled seeing a huge reddish full moon one evening while driving and fixating on it for a moment. As riders we are often reminded of the smaller window for error and as much as it pains me to say, they might have won me over, I can see how a full moon could get you into trouble. It’s important to remember the study doesn't definitively say, the full moon is the cause (any study that implicitly states causality is definitely suspect) but there is easily enough data that show that for every two full moons there is an additional rider fatality.

U.S.,Canada, United Kingdom and Australia: the results are the same

There were some interesting things that the study mentioned that I never considered. The moon just seems to be a "natural distraction". The brightness of the full moon or supermoon can create changes in perception that can cause a rider to misjudge distance and the supermoon or full moon tends to lead to more activity from humans and animals alike.

To avoid bias to the US and account for different cultures and climates, the researchers used similar data sets and replicated the entire study for Canada, the United Kingdom and Australia. The datasets were smaller for each country and therefore not statistically significant but the results matched the conclusions found in the U.S.

Super Moon at 12 o'clock (Credit:

Super Moon at 12 o'clock (Credit:

Stay focused and don't let your mind drift when you're riding under the full moon

It sounds like riders have a new risk factor to adjust for, but riders don't have to shoulder all the blame. For some reason, the full moon tends to make us take more risks, the lunacy (which is what its called) is quite real and has been documented before. In fact, the inclusion of the moon in many advertisements for cars, and vacations was what sparked this research. See: Dark side of the moon: Motorcycle deaths linked to full moons

The good news for riders is that the remedy for this risk is nothing new. Stay focused and try not to let your mind drift when you're riding. I'll give the authors kudos because their recommendations are ones I whole heartedly endorse; maximize visibility, wear protective gear, keep your bike in good working order, scan the road, think about the weather, don't stunt ride on public roads and watch out for vehicles turning left. Smart riders do these things anyway. This study may not be presenting new solutions for riders, but the next time you are out riding at night, knowing the full moon can be a factor against you could mean you'll be able to snap yourself back into focus if you catch yourself gazing at its brilliance.

The NASA graphic shows the phases of the moon

The NASA graphic shows the phases of the moon

Each moon has a different name, here's the full moon schedule for 2023!

January 6th you'll see the full Wolf Moon.

February 5th, is the full Snow Moon.

March 7th, you have full Worm Moon.

April 6th is full Pink Moon.

May 5th is full Flower Moon.

June 3rd is full Strawberry Moon.

July 3rd, you'll see full Buck Moon.

August 1st is the full Sturgeon Moon.

August 30th is the full Blue Moon.

September 29th is the full Corn Moon.

October 28th is the full Hunter's Moon.

November 27th is the full Beaver Moon.

December 26th is the full Cold Moon.

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