It is well known the tides are caused by the tidal forces that are formed through gravity between the Earth and the Moon (and also between the Earth and the Sun). To put it simply, you can say that the Moon moves masses of ocean waters. At the full moon and the new moon, the Sun, the Moon and the Earth are roughly in alignment, hence, the forces are greater and cause so called spring tides, thus a slightly higher tide. Now, many people conclude that the Moon – and in particular the full moon – ought to move and influence us people accordingly, because our bodies consist mostly of water. This claim contains several errors in reasoning, which we would like to explain in the following.
Initially, a few words about the tides again: the rise and drop of sea levels is caused by gravity which impacts the Earth from the Moon and the Sun. Due to these forces, the masses of ocean waters are virtually deformed and therefore change their relative levels at coastal areas. The water is actually shifted. These water movements take place continuously, in fact in a rhythm of approximately 12 hours 26 min for »once per tide«
Let us move on to the thought that people could be influenced by the Moon, as they predominantly consist of water.
A human is not an ocean
Assuming a human has an average weight of 70 kg and a water content of 70 %, then these are about 50 litres water per human. In contrast, there are an estimated 1.38 sextillion (1.38 x 10 to the power of 21) litres of water in the oceans. This is an inconceivable amount of water. When we look at the forces now that have an effect on our bodies from other celestial bodies, they are incredibly tiny. This would be as if a fraction of a dust particle would fall onto our shoulders …
Body is not identical with psyche
Assuming a human would be able to feel this minimal force and the shift of water in his/her body for a fraction of a millimetre, why should he/she feel better or worse? Everything in our body is in constant movement anyway: blood circulation, metabolism, respiration, digestion … all of this has a lot more significance.
Incidentally: Whoever feels depressed because of a dust particle, should on occasion, perhaps pay the doctor a visit ;-)
Tides are there every day
Assuming we would feel the forces of the Moon on the water in our body, then this ought not be the case merely at the full moon, but also at the new moon and as strongly on any other day.
In all, it becomes apparent that the thought process of a connection between the Moon and the water in our body has not achieved a convincing result. We are able to assess that we are drawn to the Moon for other reasons. It is and remains an important part in our lives, but not because we consist of water.