Updated at: 21-11-2021 - By: Jane

Moon-related health and behavior theories have been around for millennia. According to Pliny the Elder, the moon’s influence on tides, marine life, plants, animals, and human activity could be traced back to its ability to “penetrate all things.” Although some lunar phenomena, such as tides and eclipses, have been explained by science, much remains a mystery.

The moon’s power to influence nighttime behavior is one of the most common lunar myths. Many tales of midnight mayhem, sleep problems, and sleeplessness have been passed down from generation to generation because of the moon’s untapped power. What about the folklore, though? It has been revealed that lunar phases have a direct correlation with sleep.


What Are Moon Phases?

From its nightly change, the moon’s mystery originates In some nights, the orb is full and bright; in others, it fades to a barely visible crescent. An astronomical dance creates the sense that the moon undergoes an actual physical alteration each night, yet this is only an optical illusion.

Light comes from the sun rather than being generated on its own. Reflected sunlight can be seen in varied amounts from Earth depending on the position of these three celestial objects. The moon’s ever-changing shape is the result of our ever-shifting terrestrial perspective.

Each night, the moon appears to decline in size until it is totally obscured by the horizon (new moon). It takes a while for the moon to return to its full size. When the moon completes this cycle, it will take 29.5 days.

The moon’s periodic metamorphosis is broken down into eight phases, each of which indicates the exact shape formed by visible sunlight and whether the shape is expanding (waxing) or reducing (wanting) (waning). First quarter, waxing gibbous, full moon, waning crescent, third quarter, and fading crescent are the eight phases of the moon. In each phase, the moon, Earth, and sun are in a different position relative to each other.

Also keep in mind that the moon’s position in the sky changes every night as it orbits the Earth. Delaying moonrise by around 50 minutes a day is a result of this shift. It is only when the moon is directly opposite the Earth and sun that a full moon occurs. New and full moons coincide with each other, and the sun rises and sets in tandem with the moon.

Can Moon Phases Affect Sleep?

It is well known that the lunar cycle has an impact on biological rhythms in nature. Lunar cycles may influence tree diameter, crab reproduction, Great Barrier Reef spawning events, and owl monkey nighttime activities. There is a lot of uncertainty about the impact of lunar phases on people due to the small size of most studies and the lack of consistent results.

There is significant evidence, however, that lunar cycles may interfere with sleep, particularly during the full moon phase.

The full moon was found to be connected with poorer sleep in one study, which looked at a variety of metrics. When the moon was in this phase, participants had to wait five minutes longer to fall asleep, had to sleep for 20 minutes less, experienced a 30% decrease in deep sleep, and reported lower sleep quality.

While overall sleep time was reduced by 25 minutes during the full moon, arousals and awakenings were enhanced. However, the findings of this study contradict previous studies, with participants taking longer to attain REM during the new moon. More than 300 patients underwent a one-night sleep study for this third trial. A full moon has a negative effect on sleep quality, with less deep sleep and longer REM sleep times found in those studied.

Researchers investigated the sleep patterns of indigenous Argentinian populations and 464 American college students living in a major city in the most exhaustive study on this topic. In the week leading up to the full moon, no matter where they were or how much artificial light they were exposed to, all groups slept less and stayed awake longer.



Many people believe that the amount of sunlight reflected back to Earth during a full moon disrupts sleep. Hormone levels rise and fall in response to light perception are used to calibrate the body’s internal 24-hour clock. Consequently, light levels have a major impact on sleep onset and quality.

It is possible that the moon’s brightness is the primary cause of sleep disturbance. The brightness of the moon is just 7% that of the sun’s, making it a weak source of illumination. When it comes to nighttime illumination, people are typically exposed to more artificial light than the moon can reflect back to them. In addition, several studies on the effects of the full moon on sleep were conducted on overcast nights or in surroundings with no windows.

Does the Moon Phase Affect Sleep in Children?

There is a lack of research into the impact of moon phases on children’s sleep patterns, and the evidence available is hazy. One percent less sleep was recorded during the full moon phase compared to the new moon phase by over 6,000 children from 12 nations. Another study indicated that children slept better at night when the moon was full. It’s interesting to note that the researchers ascribe the extra sleep to youngsters being more active during the day, although it’s unclear whether the moon has any effect on their activity levels.

In a German study, 1,400 teens were surveyed about their sleep patterns, physical activity, and the lunar cycle. Moon phases had no effect on sleep or activity levels after three years of data collection.

The Moon, Sleep, and Mental Health

Many mental health illnesses have a two-way link with sleep, thus the potential moon impact on sleep may be particularly significant for these individuals. Luna, the Roman moon goddess, is the source of the word “lunacy.”

Recent studies have found a possible link between bipolar disorder symptoms and the moon’s phases. One study found that the mood cycles of 37 patients were typically in sync with the lunar cycle over the course of 37 years. Smaller studies have also shown a correlation between the moon phase and bipolar mood cycles, but the actual mechanism behind this remains a mystery.”

Anxiety and despair are only two of many mental health conditions that have been linked to the moon cycle. However, a number of studies have failed to find a link between the moon phase and anxiety or depression.

Are There Gender-Specific Lunar Effects on Sleep?

Ancient philosophers disagreed over the moon’s effect on female fertility22. Menstrual cycles and fertility are thought to be influenced by the moon’s phase. If this is the case, then it is feasible to think of a process by which the moon influences sleep by acting on female hormones. It’s commonly known that hormonal changes during menstruation, pregnancy, and menopause can cause sleep problems.

When it comes to women’s reproductive cycles and sleep, modern evidence is inconclusive. When it comes to a woman’s menstrual cycle, a 15-year-long study discovered that menstruation occurred right before the full or new moon.

A period-tracking smartphone app’s data was analyzed to see if there was a correlation between sleep beginning, menstruation, and the lunar cycle. There was no correlation between menstruation and the moon phase. In contrast, women whose pregnancies began when the moon was more than half full reported more restful nights. Less-than-half-full-moon women were more likely to have trouble sleeping, according to a study.

Few studies have been done to compare the impact of lunar phases on sleep between men and women. But a few research have come up with interesting results. Another study found that female participants had shorter sleep time, less Stage 4 sleep, and less REM sleep while the full moon was in the sky. This is consistent with previous findings. During the full moon, male subjects experienced an increase in REM sleep. Other studies have found that men and women sleep slightly differently during the full moon, although the results are generally inconclusive and difficult to interpret.

Sleep was shortest before a full moon

Even though we had expected that sleep was restricted during moonlit nights, we were particularly shocked by two findings,” stated de la Iglesia.

One thing that surprised us was that we did not notice a maximum inhibition of sleep exactly during the full moon nights as we had expected; instead, nocturnal activity increased and sleep was at its lowest a few nights prior to the full moon.”

When De la Iglesia first noticed it, he thought it was because there was more light from the moon in the first half of the night (because the moon rises later every night).

It was “very surprising” to see that the effect, despite being much less, was apparent even in university students living in Seattle, he said.

Study doesn’t explain how moon affects sleep

One weakness of the study is its inability to demonstrate causality between moon phase and changes in sleep, said De la Iglesia.

“It is obvious that sleep timing is synced with the moon phases, but we still don’t know how this happens,” he said.

The moon’s gravity, though, may be to blame.

We suspect that gravitational pull cycles connected with the lunar month may predispose humans to be particularly susceptible to the impacts of light, moonlight, or artificial, on the evenings near the full moon,” de la Iglesia stated.

The bottom line

On the eve of a full moon, new research shows that we sleep less than usual. The problem is that researchers don’t know why this happens.

There was no difference in the sleep patterns of persons who had no, limited, or full access to artificial lighting, researchers found. They speculate that the moon’s gravitational pull may be at blame.

Despite the lack of evidence that lunar gravity affects sleep, experts believe light in some way is to blame.

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