Weird and scary events happen during and around full moon nights, many studies show. Correlation does not necessarily imply causation; but researchers have some intriguing theories as to why the moon may wield so much power.
Naysayers over the years have tried to discount the moon's influence on animals and humans, and yet evidence continues to mount that Earth's satellite, which will be just 216,486 miles away from us on November 14, could affect the entire animal kingdom, even when we can't directly see its glow.
The consequences "are not due to the moon per se, but rather stem from a built-in clock, which may have evolved" in humans and other animals, Michael Smith of the University of Gothenburg in Sweden told Seeker.
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In a study published in Current Biology, Smith and his team investigated how lunar phases affect human sleep patterns. The researchers found that, during a full moon, people average 20 minutes less sleep and take five minutes longer to fall asleep, on average.
"However, REM sleep (during which most dreaming occurs) was actually longer around new moons, rather than being shorter around full moons," Smith said, adding that most of the test subjects - who were all healthy 18–30-year-olds - experienced 30 minutes more of REM sleep during such nights.
As for the theorized "built-in clock," he explained that humans and other animals have multiple biological clocks that serve a variety of functions. The best known is the circadian clock, which helps regulate our sleep-wake cycle.
"Anyone who's suffered from jet lag has experienced firsthand the effects of desynchronizing this 'body clock,'" he said, adding that other internal clocks are tied to seasonal rhythms.
"Lunar clocks have been demonstrated to exist in some species, so it is plausible that they also exist in humans," he continued. "Evolutionarily, such a clock would serve to regulate behavior around the moon, perhaps accounting for differences in nocturnal light."
It is suspected that our early human ancestors took advantage of the extra light to increase everything from beneficial food foraging to mating. A number of studies show that some animal predators, such as bobcats, become more active during nights with high lunar illumination versus others.
Another big cat, the lion, is greatly affected by the moon's phases, suggests a PLOS ONE study led by renowned lion expert Craig Packer. Packer, who is based at the University of Minnesota's College of Biological Sciences, and his colleagues analyzed nearly 500 documented lion attacks on Tanzanian villagers that occurred between 1988 and 2009. More than two-thirds of the attacks were fatal, with the lions consuming their victims.
The expectation might be that lions attack more just before and during a full moon, but the researchers found just the opposite.
"Predators see far better than us on moonless nights, but their advantage disappears on bright moonlit nights," Packer told Seeker. "However, after a few bright nights before the full moon, they are hungrier beginning the first night after the full moon, and those are the most dangerous nights for us, since we are mostly active in the evening rather than in the very early morning."
The discovery could help to explain why many humans fear the dark and why other traditional nighttime hunters, such as wolves and even domesticated cats, seem to vocalize more during and after full moon periods.
Lunar phases could also influence shark predation. Notably, "The 12 Days of Terror" in 1916, where five sharks killed four people and wounded one other in waters off the New Jersey coast, happened during a nearly full moon high tide. An intriguing piece of evidence is that a tributary associated with a vacation hotspot there had maximum salinity then, perhaps facilitating the arrival of larger predatory sharks like great whites or bull sharks.
More seabirds appear to be preyed upon by sharks and seals during full moon nights as well, Takashi Yamamoto, now at Nagoya University, and colleagues suggest in an Animal Behavior study.
Yamamoto and his team tracked birds called streaked shearwaters and found that these marine birds flew for longer periods and landed on water more frequently on nights with a full moon. Some were able to feast on greater food as a result, but others wound up as someone else's dinner.
Yamamoto explained to Seeker, "When birds are sitting on the water's surface at night with a full moon, it shades moonlight passing through into the sea, so predators might be able to detect seabirds using such shades."
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There is also a sexier side to full moons. Each year, stimulated by the faint blue light of a full moon, thousands upon thousands of corals engage in a mass spawning across a wide stretch of Australia's Great Barrier Reef.
Researchers at the ARC Center of Excellence for Coral Reef Studies discovered that extremely light-sensitive receptors known as cryptochromes in coral permit lunar tracking. Humans have these too, operating as part of the circadian system and possibly the theorized 'lunar clock.' Corals aren't the only animals increasing in number during full moons.
Lunar phases appear to influence jellyfish swarming and mating, such as during predictable moon and temperature-driven cycles in waters off the coast of Israel, University of Haifa scientists have found.
Further, University of Tokyo researchers led by Tomohiro Yonezawa found that spontaneous - not induced - births among genetically similar dairy cows happen more often during near full and full moon periods than at other times. Yonezawa said that he and his team "are excited to do further research because the findings should eventually lead to discoveries that can be generalized to human births."
There are still many mysteries about the moon's power over us and other animals. Part of the problem in understanding the moon's impact is that this satellite, with its 1,079-mile-wide radius, is omnipresent.
Here on Earth, we cannot escape it, even if we travel to the remotest parts of the planet or try to block out its bright glow.