This video answers the question: Can a full moon affect human behavior? This is a theory that I've heard many times and there's a lot of different behaviors that people attribute to full moons. It's believed that 80% of nurses, 70% of mental health clinicians, and 50% of the general public believe that the full moon affects human behavior and there are a lot of different areas that this belief says can be affected by a full moon. For example, increasing psychiatric hospital admissions, increasing crime, including violent crime, increasing the risk of unstable behavior or mood dysphoria, increasing the number of seizures that occur, and the number of traffic accidents. To understand this theory about the moon, we have to understand a little bit about the moon's orbit and about gravitation. First with gravitation, the moon exerts gravitational force on everything else in the universe, technically, but everything else on the planet including human beings and all the objects on the planet. The most noticeable impact of this gravitational force is the moon's effect on the oceans and other large bodies of water. We know for instance that the moon has an impact on tides. the way the theory goes is that if the moon is exerting gravitational force on the oceans, which are of course mostly water, then it's exerting gravitational force on people in some special way because human beings are mostly water (about 80% water). Next, we need to take a look at the moon's orbit and how it does or doesn't line up with the phases of the moon. A full moon ad a new moon are phases of the Moon. They don't have a relationship with the distance between the moon and the earth. The moon orbits the earth in an elliptical pattern and when the moon's closest to the earth that's called perigee and when the moon is farthest away it’s called apogee. The phases of the moon, like full moon and new moon, do not correspond with the perigee or the apogee, so when the moon is exerting the most gravitational force on a person, that's not necessarily related to a phase of the moon. Another important part here is to understand how much gravitational force the moon is actually exerting our person. To understand this, we have to understand the concept of a Newton. A Newton is a measure of force and it's the amount of force required to accelerate a one kilogram mass one meter per second per second, so it's a very small amount of force. If we think about what it feels like on a person on earth, one Newton would be about .22 pounds, so very light amount of force. Now the amount of force the earth exerts on the average human being is around 950 Newton's. The amount of force that the moon exerts on human being is about .004 Newtons. There is some evidence that there is a relationship between the full moon and some animal behavior. In terms of human beings there is evidence that a full moon can have a very small effect on sleep (less than 1% the amount that so many sleeps would be subject to change based on a full moon).
If the full moon is really not affecting human behavior, which it doesn't appear to be in any meaningful way, why do so many people believe that the full moon of affects behavior. Well for one thing, the idea that the full moon affects human behavior goes back a long way. The term “lunacy” comes from a Latin word for the moon, so this belief that unstable behavior is associated with the moon goes back many years. When you have a tradition like this, when you have a belief that goes back a long way, by default most people will of course believe it until they see evidence to the contrary. This is where a problem comes in. First of all, we tend to look at events more than nonevents. It's just a condition of human behavior. If something unusual happens we're going to notice that if it happens to coincide with a full moon. We're going to remember that coincidence more than we remember a nonevent or even an event happening when there's not a full moon. There's a bit of memory bias at work. When we believe something as we would in the case of the full moon, because this belief has been around a long time, we tend to look at evidence that confirms our belief. We are going to look at things that happen during a full moon and tend to attribute those behaviors to the full moon, instead of other more likely causes.