There are not really any solidly compelling pieces of proof that show that a full moon can make people crazy and commit crimes. But the myth surrounding this claim is greatly interesting.
Since the term ‘lunacy’, a word we use to mean ‘mad’ or ‘crazy’, is derived from ‘Luna’ meaning ‘moon’, the origins of this idea are where we will start.
In myths and stories in general, we are fond of the idea of creatures being compelled by the moon. Vampires and werewolves are two creatures of such. Both of which bear a resemblance to humans, in that a vampire was once a human, and a werewolf spends most of its time being one.
Both of these rely on the moon to either change into their real form, or to even go outside safely without burning. We are taught to fear these creatures in the stories we read, therefore, the connection to the moon has the connotation of crazy.
Studies have been carried out and show that there is no real correlation between the amount of serious crimes like murder committed and the lunar cycle. So, that covers the crime part of the question.
But the crazy part of the question is a little more interesting. Although there is evidence that more people get admitted to psychiatric hospitals when there is a full moon, there is no real evidence to suggest that this correlation is cause and effect.
The reason for people believing that the full moon can have an effect on people, making them crazy and commit crimes, could be a self-fulfilling one. Just like a placebo effect when taking pills, people could believe that the moon affects the human body and brain just like it affects the tide because it is an easy explanation.
People in the population who subscribe to this belief could also be glamorizing the idea of the moon affecting people physically and mentally, therefore increasing the amount of people that try to explain their crimes and mental illnesses away with the full moon.
There is no direct evidence to suggest that the full moon actually affects our human minds and bodies. The moon can affect the tide due to its gravitational pull, but this in itself is weak compared to that of the earth and we do not experience it in any other capacity.
The earth is covered in liquid, making it easier for it to be compelled by the moon’s gravitational pull. But as human beings, the moon cannot affect us in the same way as it affects the oceans. Therefore, there is no real evidence to suggest that a full moon can make someone crazy or commit crimes.
All we have to thank for that belief is the term ‘lunatic’ and the stories of werewolves and vampires that are so ingrained in our culture that we glamorize the idea of the full moon having any effect on us.