The Lunar Effect and other Mysteries of the Moon

Shelley, my new yoga instructor, reassures the group of us lying horizontal on the floor in savasana that the heaviness we may have been feeling over the past few days is about to lift. The moon, she says, is in a waning gibbous. I look up at her with wide eyes. It was only last night that I was complaining about the uncharacteristic bloating and lethargy my body was exhibiting. The heaviness was, and still is, undeniable.

Waiting for coffee after class, I open a tab on my phone and type ‘Melbourne Moon Today’. Google generates a detailed explanation of the Moon, which is precisely 14.65 days old at this moment; 100% illuminated with an approximate distance of 370,130.48 km from the Earth. I close my phone and stare up at the sky, it takes me a moment to locate the moon, which is a faint and fading smudge. I consider all the moon-related phenomena I have encountered over the years and wonder – is there something to it?

Where it all started: Theories of lunar impacts on humans and the world at large

Classically –thousands upon thousands of years kind of classic– different moon phases have been linked to variations in sleep, menstruation, mental health and even aggressive or violent behaviours. In the same way that the earth’s oceans are subject to tides, philosopher Aristotle believed the high-water content of the human brain also makes us vulnerable to shifts in the moon. This provoked subsequent theories about the ‘tides’ of the mind, whereby the full moon (corresponding to the highest tide) was linked to imbalances in human physiology to the likes of seizures, violence, and mental ill-health. Eventually, by the 16th century, stalking the Moon’s orientation was deemed an essential part of medicine.

Today, thanks to pop-culture references, social media and the tradition of storytelling, there appears to be a mix of viewpoints when it comes to the moon’s effects on human behaviour. Some will joke about it, others take it very seriously. I’d never thought too much about where I sit on this spectrum. It’s only after hearing Shelley speak to something real within me that I hadn’t told her about, that I feel compelled to probe if there is science and modern medicine to back up these long-stated claims about the moon’s power.

Unpacking assumption #1: The moon and sleep

We’re all prone to sleep disturbances, some more regularly and profoundly than others. Some people tend to be superstitious about these disturbances, attributing them to the fullness of the Moon. A 2013 study sought to measure changes in sleep across the lunar cycle in the controlled conditions of a sleep laboratory. This study found that during a full moon, participants took an average of 5 additional minutes to drift to sleep, slept an average of 20 minutes less overall, and experienced 30% less time in deep sleep, when compared to the rest of the month. Convincingly, these highly controlled laboratories meant participants were not exposed to any moonlight or knowledge as to which phase the moon was in. This served to eliminate sensorial factors, or expectation bias, from contaminating the results.

While these results suggest the moon really does mess with our sleep, the two follow-up studies that sought to replicate this, unfortunately, failed miserably. This has left scientists, and the rest of us, with little insight into whether moon phases really do or do not influence our capacity and quality of sleep. It could still be purely psychosomatic (i.e. you expect to sleep poorly, so you do) rather than scientific. This one remains a mystery!

Unpacking assumption #2: Moon and menstruation

This link feels to me to be the most coherent, perhaps because of the mutual association with the calendar month. Physician Richard Mead published a book in 1708 that proposed the moon and menstruation are inextricably linked. Mead believed that the Moon has a substantial role in forcing “evacuations” of menstrual blood in women. He also claimed the Moon’s influence was more profound for females living closer to the equator.

The word moon is often said to be traced back to the old English word mona, derived from Latin words metri (meaning to measure), and mensis (meaning month). However, this might be the only link between the moon and menstruation, according to modern medicine and technology. Clue, the popular smart phone application for tracking female periods, tried to set the record straight in 2016. Researchers gathered data that would reveal whether an association exists between the moon’s phases and menstruation – no link was found. Lead scientist involved in this study, Dr Marija Vlajic Wheeler, concluded that periods are not picky. Instead, they are scattered uniformly across all the lunar phases. Similarly, a complex analysis of archived birth records across major international hospitals undermines my sister’s claim that working on a full moon in the birthing suite means a busier shift.

Unpacking assumption #3: Moon and mental health

The idea that the full moon is linked to anger, aggression or violence and mental illness is commonly reinforced by popular culture and cinema. How many of us have superstitiously said something to the likes of ‘it must be a full moon tonight’, in response to chaotic phenomena in the night or when witnessing extreme behaviour? There is even a strong language-based link between the full moon and mental ill-health, as the Roman goddess of the moon ‘Luna’ is a prefix to the common, albeit derogative, term ‘Lunatic’.

I probed a colleague about her knowledge of the moon, and she explained that her sister, an emergency department nurse, believed that full moons coincide with busier shifts. Apparently, presentations at this time are always more extreme, with reports of greater emotional instability or mood swings. However, in a study of 17,966 individuals over a ten-year period at various psychiatric wards, no link was found between the moon phases and cases of mental hospital admissions or discharges.

So, are we all just collectively gullible…?

So, what then? Is the lunar effect a sham? Is our interpretation of reality informed only by allegory? That is, are we all just collectively gullible? Not exactly. For one thing, humans have a tendency to assume associations between otherwise unrelated events when we are expecting there to be a link –  a concept otherwise known in the psychology world as confirmation bias. This bias means that we are more likely to read meaning into any anomalies such as disrupted sleep, mood or busier work shifts that occur around the time of expected lunar shifts. At the same time, we tend to be more likely to disregard any events that don’t fit in with our pre-existing beliefs or expectations, such that the same anomalies occurring outside of meaningful moon states tend to be disregarded or forgotten.

Nevertheless, beyond the impact of our expectations and perceptual biases, scientists have not completely ruled out the moon’s impact on us and the Earth. The moon becomes full every 29 – 30 days, and new 14-15 days after this, so the shifting provision of moonlight is one thing that it clearly offers us. While our tools are not yet advanced enough to fully understand and quantify how the moon impacts on the earth’s magnetic field, there is also some very early research to suggest that humans, like other animals (such as migratory birds and fish), can subtly sense our earth’s magnetic field. If this is the case, maybe there is something deeper in the way the moon might affect people.

The moon is a mysterious thing, and perhaps that’s where it’s beauty lies

In sum, the changes in light and gravity at each moon phase make slight, intangible adjustments to the atmosphere we live in. Although we may not yet be able to measure it, many scientists still purport that there might be something to our superstitions regarding the moon. Therefore, it seems that the popular approach is to refrain from discounting the lunar effect altogether, and agree that the moon may affect how we make choices, we’re just not sure how yet.

I am humbled by this inconclusive conclusion and the idea there is something powerful and complex in our atmosphere that pushes and pulls us in ways we are not yet able to comprehend. And regardless of how factual our assumptions about the moon are, it’s a good reminder that we are a part of something greater.

Check out this link if you’re keen to read more about the potential impact of the full moon! You can also read further about how our natural world can positively impact our mental health here.