Lunar effect

The lunar effect is the idea that the Moon's changing phases and position might influence the behavior and biology of different living things on Earth. The Moon goes through a cycle of about 29.5 days, which changes how much light we see at night and affects the rising and falling of ocean tides. Many animals and plants have developed ways to follow this regular pattern.

Scientists have studied whether the Moon affects humans, looking at things like mood changes and birth rates. By the late 1980s, there were many studies on these ideas, but overall reviews have found no real connection between the Moon and human biology or actions. For example, the monthly cycle of menstruation in humans happens around the same time as the Moon's cycle, but this seems to be a coincidence rather than a true influence.

In the ocean, however, some animals clearly respond to the Moon. Corals, for example, have special proteins that sense light and often release their eggs at certain points in the lunar cycle, such as around the last quarter moon. Similarly, a type of bristle worm called Platynereis dumerilii releases its eggs a few days after the full moon. These creatures use the Moon's light as a signal to time important events in their lives.

Human contexts

Claims have been made about the Moon affecting human fertility, birth rates, and behavior. Many believe the Moon influences fertility because the average menstrual cycle is about 28 days, similar to the Moon’s cycle. However, studies have shown no real connection between the Moon’s phases and when people’s menstrual cycles start.

Researchers have looked closely at whether the Moon affects how many babies are born. Many studies from different places, like Danville, Pennsylvania, UCLA, Phoenix, Arizona, North Carolina, and Hannover, found no link between the Moon’s phases and birth rates. One large study in France did find a very small increase in births on the day of the full Moon, but it was so small that it would be hard to notice in a hospital.

Some people also think the Moon affects human behavior. For example, police in places like Brighton, Ohio, and Kentucky have noticed more unusual behavior and crime during full moons. However, many studies do not support this idea. Research on crimes, seizures, and even stock market performance show mixed or no results.

Studies on sleep have also given mixed results. Some suggest people sleep less near the full Moon, while others find no change or even more sleep. Scientists are still trying to understand if and how the Moon might affect our sleep and behavior.

Main article: Menstruation § Effects of the moon

Other organisms

Many animals use the light from the Moon to help them move and decide when to do certain activities. For example, some insects, like moths, use moonlight to help guide their flying. Corals, such as those at the Great Barrier Reef, release their eggs and sperm after the full moon in certain months. Other sea creatures, like fish and worms, also time their breeding to match the Moon’s phases.

Plants and seaweeds can also be influenced by the Moon. Some types of seaweed release their spores based on the lunar cycle. Scientists are still studying whether certain plants change their growth with the Moon.