Does The Moon Affect Our Mood? 

For centuries the full moon has held significant supernatural power over mankind. Biologists, artists and poets have all pondered the effect of our 29.5 day lunar cycle and how it has a physiological effect upon the Earth.

So let’s talk about our Moon, which interestingly doesn’t even have a name considering all other solar system moons have been given names. Jupiters moons; Ganymede, Io and Callisto are all larger than ours as is Saturn’s moon Titan.

To us it is just “The Moon”, our only moon which is tidally locked with the Earth. By tidally locked, we see only one side of it. As we are on the topic of clearing up misconceptions, there is no dark side of the moon either. The other side receives the same amount of light as the front, although the side we see as illuminated is the side that faces us.

From the astrophysical side, the mass off the moon is 7.342×1022 kg and a total surface area of 3.793×107 km2. They might seem like large figures but both are less than 1% of the Earth mass and surface area figures. The moon does have an influence on our ocean tides, land tides and net reflected sunlight here on Earth. 

In terms of mood and wellbeing, people believe that because the Moon’s gravitational power and energy can control tides it can control our hormonal systems in our bodies. In sticking with this line of thinking, surely tides would have an effect on lakes, swimming pools and cups of coffee aswell. 

The mass of the moon is permanent. The mass and gravitational power of the moon, which in physics isn’t a great deal of power, is exactly the same in a half moon. The moon doesn’t warp or bend the fabric of space and time more when we see more of it in a full moon. All other laws of physics such as intrinsic angular momentum and orbital mechanics are exactly the same and have the same effect regardless of wether we see all of the moon or half of it. High tide is high tide when there is no moon visible to us here at all.

There have been studies from the medical perspective that full moons can affect blood clotting and psychiatric illness but from the eyes of science they fall into the margins of statistical fluctuation and the margin of error. Certainly there seems to be heightened sensitivity and awareness during a full moon. 

Interestingly the 2017 Nobel Prize in Medicine was awarded to Jeffrey C. Hall, Michael Rosbash, and Michael W. Young for the analysis of the Circadian Clock in living organisms. There is mention of lunar cycles operating within the same laws of nature but the exact link between it and the internal body clock isn’t entirely clear and so far their research has been taken out of context for firm believers of the lunar effect on our bodies.

The moon does have a relatively tiny mass within the solar system and the observable universe. If anything were to hypothetically “pull our hormone levels” it would surely be the Sun? The sun does have effect on tides although a smaller one.

 Even closer bodies like Jupiter, Uranus and Neptune which are all massive bodies that travel in the single speed straight line through the curved spacetime should affect human behaviour. Surely these closer and more massive objects should have an effect on us but the simple fact is they don’t. The same way the moon doesn’t. 

The Lazer Interferometer Gravitational Wave Observatory (LIGO) detected the collision of two black holes which sent ripples of space and time through the Earth. On that day the Earth didn’t fall into anarchy. Here we are. That incident was two supermassive black holes colliding around 4 billion years ago and merging to send a shock wave throughout the universe. 

By day I pass myself as a mental health professional between 9am and 5pm and I have discovered that the belief of the lunar effect is quite large. Trying to discuss this as a physicist and cosmologist is quite difficult due to the hardened belief of this effect. It also quite rightly serves to deepen some of the misconceptions and stigma of mental illness, quite sad really.

Jude Morrow

2 thoughts on “Does The Moon Affect Our Mood? 

  1. The words ‘lunatic’ and ‘lunacy’ do derive their etymology from the moon – originally considered a “moon madness”.

    Another interesting podcast on the moon’s influence on earth (from a physical point of view rather than a mental health perspective) is available here from BBC World Service;


    1. Thank you for your comment Jeremy! The moon does have an influence on the Earth but more due to popular culture than scientific reason.


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