There are dozens and dozens of myths about the moon and its strange effects on humans. Some persist even if they are proven wrong: menstrual cycles do not keep pace with the lunar cycle, "supermoons" do not cause "insanity," and the full moon does not have an explicit gravitational effect on humans. In truth, a mosquito perched on your arm has a stronger gravitational effect on you than the moon. So, is everything folkloric? Not too much. In recent times, science may have finally discovered something true about the moon's effect on human behavior in the area of sleep. A new study from Uppsala University, Sweden, published in the January XNUMX issue of Science of the Total Environment, finds an association between the lunar cycle and sleep. He also discovered that the lunar cycle can influence men's sleep more than women's. To understand why, and how scientists found it, it helps to know the cycle of the moon and how its light changes over the course of a lunar month.
How the moon and moonlight march
The moon orbits the Earth every 7 days from east to west, changing its illumination as it does. Since night light disrupts sleep in humans, this is vital, as is moonrise around fifty minutes later day after day. Throughout its development period, from the new moon to the full moon, the amount of illuminated lunar surface seen from Earth increases. It takes 7 days for the moon to go from a crescent moon, which does not emit much light and sets just after sunset, to the first quarter, that is, when the lunar surface appears to be half-lit and is "high." for the middle of the night. So it takes another XNUMX days for the moon to grow from first quarter to full, but the difference in light it emits is astounding; a moon in the first quarter is only XNUMX% brighter than a full moon. After the full moon, our natural satellite wears out over fourteen days, appearing less illuminated and rising very late at night. Thus, it is the first half of the moon's orbit that can disrupt sleep patterns. This is because humans fall asleep most of the time after dark and until dawn; Moonlight won't wake us up, but it can delay us from falling asleep.
Sleep and the lunar cycle
Swedish scholars matched the records of a night's sleep in the home of XNUMX women and XNUMX men, bearing in mind the precise phase of the moon. "We found that men whose sleep was recorded along the nights of the waxing period of the lunar cycle had decreased sleep efficiency and increased wakefulness after sleep onset," said Christian Benedict, an associate professor in the department of neuroscience at Uppsala University and corresponding author of the study. This was on par with men whose sleep was measured over the nights of the waning period of the moon. There was another surprise. "Women's sleep has remained largely unchanged by the lunar cycle," Benedict said. The study adjusted for chronic sleep problems and sleep apnea, which are known to affect human sleep.Men and the moon
The authors suggest that the moon can affect the sleep of both men and women when its light is high in the sky at times when people usually go to bed, just before the full moon. So why are men more sensitive to moonlight? The authors cite two studies to support their findings: one suggesting that the male brain may be more sensitive to ambient light than the female brain, and another reporting that blood melatonin levels were lower throughout life. full moon compared to new moon. . among twenty male subjects. The human sleep-wake cycle is controlled by melatonin, a hormone that is released predominantly at night. This isn't the first evidence of what scientists call "circalunar rhythmicity" in humans. The first reliable evidence that a lunar rhythm can modulate sleep in humans was found in a study of 2 of 5 people. "The evidence that the lunar cycle influences human sleep" observed that during the full moon, the subjects tended to take, on average, XNUMX minutes longer than usual to fall asleep, they had XNUMX% less deep sleep and slept twenty minutes less. In short, the quality of sleep suffered, but the sample was small.
Moonlight vs artificial light
These findings were bolstered by a much larger investigation, both in size and scope, published in the January 3 issue of Science Advances. In "Dazzling Sleep: Synchronizing Human Sleep with the Lunar Cycle under Field Conditions," a team of researchers led by University of Washington neurobiologist Horacio de la Iglesia found that increased moonlighting affects sleep habits. This experiment matched the sleep patterns of ninety-eight residents of western Toba/Qom Formosa, northeastern Argentina, an old indigenous hunter-gatherer community. They were divided into 3 groups; twenty-five without access to artificial light, thirty-three in rural areas with limited access to electricity, and forty in urban areas with simple access to electricity. The results were matched with a control set of 5 college students in Seattle, Washington in the USA from a separate investigation. They all wore a Philips Actiwatch Spectrum Plus to track their sleep/wake patterns. The results were revealing in more ways than one, with the researchers finding similar sleep patterns for everyone over a full XNUMX-night lunar cycle. Location and access to electric lighting were not factors. In the XNUMX to XNUMX nights prior to the night of the full moon, the participants took longer to fall asleep and slept as little as possible during this time.