Lunar effect

The lunar effect is the idea that the Moon's changing phases might influence living things on Earth. The Moon goes through a cycle of about 29.5 days. This cycle 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 pattern.

Scientists have studied whether the Moon affects humans. They looked at things like mood changes and birth rates. Reviews of many studies 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.

In the ocean, some animals respond to the Moon. Corals have special proteins that sense light. They often release their eggs at certain points in the lunar cycle, such as around the last quarter moon. 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 to time important events in their lives.

Human contexts

Some people believe the Moon affects human fertility, birth rates, and behavior. This idea comes from the fact that the average menstrual cycle is about 28 days, which is similar to the Moon’s cycle. But studies have not found a real connection between the Moon’s phases and when menstrual cycles start.

Researchers have checked if the Moon affects how many babies are born. Studies from many places, such as Danville, Pennsylvania, UCLA, Phoenix, Arizona, North Carolina, and Hannover, did not find a link between the Moon’s phases and birth rates. One study in France found 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.

Some people also think the Moon affects human behavior. For example, police in 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 stock market performance has shown mixed or no results.

Studies on sleep have also had mixed results. Some suggest people sleep less near the full Moon, while others find no change or even more sleep. Scientists are still learning 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 things. 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 some 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.