Many myths and legends suggest the phase of the moon can affect behaviors. Folklore about werewolves even suggests it can have transformative powers. Though we may not change species according to the moon cycles, there is research to suggest they do affect us.
This poses the question: Do lunar cycles affect how you sleep? To answer that question, we first have to understand what lunar cycles are all about.
What are the Different Moon Phases?
The moon goes through different “phases” that repeat every 29.5 days. These phases are defined by how much of the moon is visible from earth. It is these phases that are referred to by the terms “lunar cycles” or “moon cycles.”
According to NASA, “Because of the tilt and shape of its orbit, we see the moon from slightly different angles over the course of a month.” The moon’s phases range from a full moon — that’s when the moon looks like a full circle — to a half moon, small crescent, and then a new moon, where the moon isn’t visible at all.
Do the Moon Phases Impact Sleep?
According to some research, there may be a small link between the moon’s phase and how well people sleep.
It is hypothesized that the extra light emitted earlier in the evening and afternoon hours, leading up to the full moon, can create a change in our circadian rhythm, which will affect our sleep. The lunar cycle seems to affect both quality and quantity of sleep, similar to what we see in shift workers and those suffering from jet lag who are exposed to light at irregular times.
In a recent study, researchers from the University of Washington studied two groups: First the indigenous Toba/Qom communities in Argentina, and later college students in Seattle. They found a link between the waxing full moon and the shortest amount of sleep. Both groups had the latest bedtimes for about three to five nights leading up to the full moon.
Within the indigenous Toba/Qom community, the researchers followed three specific segmented groups: one very rural segment with virtually no access to electrical light, one moderately rural segment with 24 hour access to minimal electrical light, and one urban group with access to lights at home and within the community setting — the Seattle college students fell into this group, too.
These findings indicated that the moon’s phases do affect sleep, and that the more limited one’s access is to electrical light, the stronger the moon’s effect on sleep.
Leandro Casiraghi, UW postdoctoral researcher in the Department of Biology and the lead author of the study said, “We hypothesize that the patterns we observed are an innate adaptation that allowed our ancestors to take advantage of this natural source of evening light that occurred at a specific time during the lunar cycle.”
The same researchers discovered that the new moon, or dark phase of the moon, also created a smaller but noticeable change in sleep patterns in the two more rural segments of the Toba/Qom communities, suggesting that the sleep changes may also be caused by something like the moon’s maximal gravitational pull rather than by the full moon’s light. More research is needed to fully understand these complex sleep changes.
According to NASA, humans experience the strongest gravitational pull during the full and new moons. At full moon, the moon and sun are essentially in a straight line on the opposite side or the same side of the earth respectively, and in both cases, the gravitational forces combine to create a pull on the earth’s surface.
How the Moon Can Impact Sleep
Many people feel more restless, have difficulty falling asleep or getting up at regular times and report more vivid dreams during the full moon. Studies show that the full moon does affect REM sleep, melatonin levels, and it inhibits our sleep efficiency in general.
Restlessness and more vivid dreams
Psychologist Richard Wiseman from the University of Hertfordshire, UK, analyzed the results of 1000 volunteers who listened to specific sounds that his team played as they slept. Wiseman discovered that for about a week surrounding the full moon, the content of our dreams are noticeably, “more strange”. He went on to describe that, for instance, “someone might dream that they are flying on a dragon, then get off the dragon and go have a coffee with George Clooney, while some people dreamt that they were superheroes.” Professor Wiseman also notes that, “our ancestors may have hunted when the moon was full, with the result that we still find it hard to settle on bright nights.”
Difficulty falling asleep or getting up at regular time
Results from a highly controlled Swiss study, where participants were put in sleep chambers with no access to windows, electronics, or had the ability to know what time of day it was for three and half days around the full moon, showed that:
- They slept 20 minutes less overall.
- They took 5 minutes longer to fall asleep.
- They had a 30% decline in brain activity that relates to deep sleep.
- They had lower levels of melatonin—which is our master regulator hormone of sleep and wake cycles. When melatonin is lowest, we tend to be awake and when it is highest, we become sleepy.
- The participants reported feeling less rested during the same period.
Meanwhile, in a smaller study performed with men and women in Surrey England, women had shortened sleep and less REM sleep around the full moon, while men’s REM slightly increased during the same period.
Why Can’t I Sleep During a Full Moon?
In one study, researchers analyzed data from 5,812 children in 12 countries who were aged 9 to 11 years. According to Psychology Today, the researchers discovered that “Children slept an average of 4.9 minutes less during the time of the full moon, compared to the time of a new moon, an average 1 percent reduction in total sleep time.”
Scientific American reported on another study of 33 individuals, which found that “around the full moon, humans get less shut-eye and their slumber is not as deep, even if sleep is restricted to windowless rooms free of environmental and time-based cues — such as those found in a sleep lab.”
Study author Christian Cajochen, from the Psychiatric Hospital of the University of Basel in Switzerland, told CNN, “If you ask people, at least in Switzerland, about 40 percent report feeling the moon during sleep, or they blame the full moon for bad sleep.” Researchers aren’t totally sure what might cause the alleged connection between sleep and lunar cycles, but it could be related to our circadian rhythms.
Circadian rhythms are mental, physical, and behavioral changes that follow a cyclical 24-hour pattern that respond primarily to light and dark. Most living things, including animals, plants, and microbes are affected by circadian rhythms.
It is theorized that the moonlight affects circadian rhythm in a similar way that exposure to electrical nighttime light does; by inhibiting melatonin synthesis—a key hormone that is produced to help us sleep. It may also be a leftover effect of our ancestors’ harmony with the lunar cycle.
Scientists know that available moonlight changes formulaically throughout the moon’s cycle depending upon the time of moonrise, which is approximately 50 min later every day. The theory is that there is extra light available to us just after dusk, as the moon waxes toward full, because for these three to five days the moon is higher in the sky in the late afternoon and early evening instead of at its brightest in the middle of the night. Belief is that access to this early evening light allowed our ancestors to do more foraging and hunting on these nights, unlike nights where the sky was darker.
A recent study by the University of Washington showed how the moon’s 29.5-day cycle affects our sleep patterns through our circadian rhythm. This study shows a clear indication that for three to five days before the full moon, we see the most disturbed sleep across all populations, whether they live in rural environments with less access to electric light or urban dwellers who tend to have an abundance of electric light in the evening. Researchers noted that people living in urban environments did have less fluctuation in sleep than those living in more rural settings, likely because the urban dwellers had consistent exposure to electrical light at night through street lamps and other city light pollution, so their sleep valleys and peaks were more suppressed.
Menstrual function has an effect on the circadian rhythm too, and it is also intimately related to the moon’s 29.5-day cycle. A long-term study done on a group of 22 women of varying ages found that all of the women (apart from three who lived in more urban environments and were self-reported “night owls”) had menstrual cycles that were synced with the moon cycles at times, either beginning around the new or full moon— full moon menses were the most prominent.
This study found that as women age or are exposed to more artificial nocturnal light, the menstrual cycle shortens or lengthens and loses this synchronicity to the lunar cycle. In ancient times, humans’ reproductive behavior was probably more synchronized to the moon, but our modern lifestyles, including later sleep onset and exposure to electrical light has likely changed this.
What’s clear is that more research is needed to determine whether our sleep is actually affected by lunar cycles. So far, preliminary research suggests the moon’s cycles might impact our sleep — but this research is hardly definitive.
The good news is no studies have confirmed that a full moon is more likely to turn you into a werewolf.
How to Sleep Better During a Full Moon
We have no control over the waxing and waning of the moon, but we do have the ability to change specific environmental factors that may help us sleep better in general, and during the full moon. Here are some sleep hygiene tips to help you sleep better:
- Invest in blackout blinds. This will block ambient light from street lamps, cars, or a bright full moon.
- Try a sleep mask. This is a great option for those who travel a lot or don’t have access to blackout blinds.
- Try a bath before bed. Cooling down after the bath is what signals sleepiness. Take the bath one to two hours before your target bedtime. It takes our bodies about 20 minutes to respond to a warm bath by cooling down our core temperature. Maximum sleepiness occurs when core body temperature is at its lowest.
- Limit your exposure to blue light for a few, or at least two hours before turning in to ensure a deep sleep.
There is still a lot we don’t understand about how the moon affects us, however the science is clear that there is a small, but direct link between the moon’s cycle and our sleep. Circadian rhythms, REM, melatonin production and menstrual cycles have all been proven to be affected by the lunar cycle.
Recent evidence points to possibilities that both the early evening light leading up to the full moon and the moon’s gravitational pull may be a key influencer of our sleep during the full and new moons. Perhaps “lunar rhythms” were passed down from our ancient ancestors who became attuned to the changing moon based on their altered daily practices around the moon’s cycles.