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  • Writer's pictureAlan Frischer, MD, MPH

The Moon and Health

Have you ever witnessed odd behavior and attributed it to the full moon? For centuries, the moon and how it affects us has been a focus of mythology and folklore. Consider the word “lunacy.” It dates back to the 15th century, when it was commonly believed that the moon and its phases could cause aggression or other behaviors. In some cultures, the moon is worshiped, and in others it holds a darker tone (werewolves!). Is there scientific evidence behind whether or how the moon affects us?

All organisms have natural biological cycles. The moon, with its month-long cycle, exerts a gravitational pull on Earth powerful enough to affect the ocean tides. Given that our bodies are made up of roughly 60% water, isn’t it reasonable that we may be impacted as well?

It is interesting that several species have adapted their biological cycles to line up with the lunar cycle. For example, the reproductive cycles of marine animals (including tropical corals, annelid worms, and multiple other species) adjust their feeding, migration, molting and more on the moon’s cycle. Another obvious example is the (typically) 28-day human menstrual cycle.

How might lunar cycles affect our sleep? Well controlled studies on sleep and the moon have shown conflicting results. One showed 20% lower levels of melatonin during full moon, and a few studies from 2021 showed a correlation between full moons and decreased sleep. Many studies were performed in well-lit sleep labs, making conclusions questionable. It’s clear that bright light from cell phones, televisions, computer screens, and certainly full moons, impacts our ability to fall asleep and to stay asleep. This makes such studies difficult to perform and analyze.

How might the phases of the moon affect mood and mental health? It is clear that various environmental factors can play a significant role in mood swings and act as a trigger for depression and anxiety. One small study on those with bipolar disorders found that they cycled between depression and mania in sync with the lunar cycle. Clearly, more research is needed.

We’ve all heard about the full moon causing altered behavior, higher birth rates, increased visits to emergency rooms, and higher crime rates. However, scientists today generally believe that while there is indeed a correlation between lunar cycles and various activities, no causation has been proven.

My instincts tell me that the cycles of the moon may very well affect our health and behavior, but scientific studies have not proven it. I suspect that most of us will continue to believe that there is an effect, and as a result, our behavior might change, based on this belief. The power of belief looms large in folklore, mythology and religion, and it makes sense that the power of belief in science as well may have a direct impact on our physical, mental and emotional health.

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