Can the full moon affect your health?

The full moon has been associated with strange human behaviour for centuries. Still today many believe that the lunar cycle has influence over our health. But what does science have to say about the full moon’s effect on humans? Is there a fact-based correlation, or is it just folklore?

It’s the stuff that legends and bad movies are made of (remember Teen Wolf?). The clouds part in the night sky to reveal a bright, full moon and, suddenly, people on Earth start to act a little crazy. Coincidence? Many think not.

[Photo Credit: iStock.com/Grigory Bruev]

At all times in Earth’s sky, half of the moon is illuminated by the sun. Most of the time, though, we see the Moon in part shade. The Moon looks full when it’s directly opposite the Sun and we’re able to clearly see one whole side of it—basically when the Moon, the Earth and the Sun are in perfect alignment. This happens about once a month. Technically the full moon lasts just one day, but the Moon appears full for two-to-three days. You’ve certainly heard of a blue moon, and maybe even a pink full moon, but these are in name only. The Moon doesn’t actually change colour, although its appearance can vary depending on particles in the atmosphere.

You have to go all the way back to ancient Rome to understand the beginnings of lunar effect theory. Pliny the Elder, a Roman philosopher, was among the first to make the link, suggesting the full moon caused more dew to form both on the ground and within the human brain, which caused people to act like, well, lunatics. In fact, the Latin word for moon (luna) morphed into lunaticus meaning ‘moon struck’—a person who suffers from periods of insanity during the full moon.

The Moon has a clear and proven effect on the Earth and its inhabitants. The moon’s gravitational pull attracts the Earth’s water towards it, creating high and low tides. Scientists have also found that the full moon benefits and shapes the lifecycle of many birds, insects and sea creatures.

When it comes to humans, however, the relationship is less clear. The full moon has been blamed for increases in everything from mood swings to headaches, insomnia, seizures and even criminal activity. One old wives’ tale suggests that more babies are born during the full moon, but statistics don’t support this theory. For nearly every study that found a causal link between the full moon and human behaviour or health outcomes, there are several more that discredit those findings. The one exception seems to be the link to sleep disturbances.

Multiple credible studies have reported that participants took longer to fall asleep, and slept less deeply, immediately before and after the full moon. What isn’t understood is why the lunar cycle seems to influence human sleep. What is clear is that theories will endure and evolve as our understanding of the special relationship between the Earth and the Moon continues to grow.