The moon looms large in folklore, urban
legends and myths from around the
world. And on Monday Nov. 14, it will
loom larger in the sky than it has in
decades.
Every full moon is a spectacular sight, if
skies are clear. But November's full
moon is far from ordinary. It will be the
closest full moon since 1948, and we
won't see another full moon this close
again until 2034, according to NASA.
Because the moon follows an elliptical
path around Earth, sometimes it is
closer to us — at its closest, a position
called "perigee," it is 14 percent closer
to Earth than when it is at its farthest
position, known as "apogee." When that
proximity coincides with the full moon
phase, making the moon 30 percent
brighter in the night sky, the event is
referred to as a "supermoon."
The moon holds a mystical place in the
history of human culture, so it's no
wonder that many myths — from
werewolves to induced lunacy to epileptic
seizures — have built up regarding its
supposed effects on us.
"It must be a full moon," is a phrase
heard whenever crazy things happen
and is said by researchers to be
muttered commonly by late-night cops,
psychiatry staff and emergency room
personnel.
In fact a host of studies over the years
have aimed at teasing out any
statistical connection between the moon
— particularly the full moon — and
human biology or behavior. The majority
of sound studies find no connection,
while some have proved inconclusive,
and many that purported to reveal
connections turned out to involve flawed
methods or have never been
reproduced.
Reliable studies comparing the lunar
phases to births, heart attacks, deaths,
suicides, violence, psychiatric hospital
admissions and epileptic seizures,
among other things, have over and over
again found little or no connection.
One possible indirect link: Before
modern lighting, the light of a full moon
have kept people up at night, leading to
sleep deprivation that could have
caused other psychological issues,
according to one hypothesis that awaits
data support.
Below, I'll review several studies — the
good, the bad and the in between — but
first some basic physics:
The moon, tides and you
The human body is about 75 percent
water, and so people often ask whether
tides are at work inside us.
The moon and the sun combine to create
tides in Earth's oceans (in fact the
gravitational effect is so strong that
our planet's crust is stretched daily by
these same tidal effects).
But tides are large-scale events. They
occur because of the difference in
gravitational effect on one side of an
object (like Earth) compared to the
other. Here's how tides work :
The ocean on the side of Earth facing
the moon gets pulled toward the moon
more than does the center of the
planet. This creates a high tide. On the
other side of the Earth, another high
tide occurs, because the center of Earth
is being pulled toward the moon more
than is the ocean on the far side. The
result essentially pulls the planet away
from the ocean (a negative force that
effectively lifts the ocean away from
the planet).
However, there's no measurable
difference in the moon's gravitational
effect to one side of your body vs. the
other. Even in a large lake, tides are
extremely minor. On the Great Lakes,
for example, tides never exceed 2
inches, according to the National
Oceanic and Atmospheric Administration
(NOAA), which adds, "These minor
variations are masked by the greater
fluctuations in lake levels produced by
wind and barometric pressure changes.
Consequently, the Great Lakes are
considered to be essentially non-tidal."
That's not to say tides don't exist at
smaller scales.
The effect of gravity diminishes with
distance, but never goes away. So in
theory everything in the universe is
tugging on everything else. But:
"Researchers have calculated that a
mother holding her baby exerts 12
million times the tide-raising force on
the child than the moon does, simply by
virtue of being closer," according to
Straightdope.com, a Web site that
applies logic and reason to myths and
urban legends.
Consider also that tides in Earth's
oceans happen twice every day as Earth
spins on its axis every 24 hours, bringing
the moon constantly up and down in the
sky. If the moon's tugging affected the
human body, one might presume we'd be
off balance at least twice a day (and
maybe we are).
Studies of full moon effects
Here are some of the reputable studies
in peer-reviewed journals that have
failed to find connections:
Epilepsy:
A study in the journal Epilepsy &
Behavior in 2004 found no connection
between epileptic seizures and the full
moon , even though some patients believe
their seizures to be trigged by the full
moon. The researchers noted that
epileptic seizures were once blamed on
witchcraft and possession by demons,
contributing to a longstanding human
propensity to find mythical rather than
medical explanations.
Psychiatric visits:
"The belief that the lunar cycle is
associated with the onset and severity
of psychiatric symptoms has persisted
since the middle ages," researchers
write in 2014 in the journal ISRN
Emergency Medicine . Has this belief
been proved out by science?
A 2005 study by Mayo Clinic
researchers, reported in the journal
Psychiatric Services, looked at how many
patients checked into a psychiatric
emergency department between 6 p.m.
and 6 a.m. over several years. They
found no statistical difference in the
number of visits on the three nights
surrounding full moons vs. other nights.
For the 2014 study, researchers led by
Varinder Parmar of Queen's University
in Ontario, Canada, looked at
psychiatric emergency-department visits
around the night of the full moon: six
hours, 12 hours and 24 hours before
and after a full moon. During the 12
hours before and after a full moon, EDs
saw significantly more patients with
personality disorders as well as with
more urgent triage scores (those who
needed more urgent care). However,
fewer patients with anxiety disorders
showed up during the 12 hours and 24
hours prior to and following the full
moon.
Lunacy:
People don't seem to be "howling at the
full moon," at least according to the
research out there.
A review, called a meta-analysis, of 37
published and unpublished studies
regarding a link between the full moon
and "lunacy" as well as other behaviors
found that just 1 percent of the change
in activities considered "lunacy" —
mental hospital admissions, psychiatric
disturbances, crisis calls, homicides,
and other criminal offenses, according
to the researchers — could be attributed
to the full moon, the scientists wrote in
their study published in 1985 in the
journal Psychological Bulletin.
Emergency Room Visits:
Researchers examined 150,999 records
of emergency room visits to a suburban
hospital. Their study, reported in
American Journal of Emergency
Medicine in 1996, found no difference
at full moon vs. other nights.
Surgery Outcomes:
Do doctors and nurses mess up more
during the full moon? Not according to
a study in the October 2009 issue of the
journal Anesthesiology. In fact,
researchers found the risks are the
same no matter what day of the week or
time of the month you schedule your
coronary artery bypass graft surgery.
Not all studies dismiss lunar influence.
Pet Injuries:
In studying 11,940 cases at the
Colorado State University Veterinary
Medical Center, researchers found the
risk of emergency room visits for pets to
be 23 percent higher for cats and 28
percent higher for dogs on days
surrounding full moons. It could be
people tend to take pets out more
during the full moon, raising the odds
of an injury, or perhaps something else
is at work — the study did not
determine a cause.
Menstruation:
This is one of those topics on which you
will find much speculation (some of it
firm and convincing-sounding) and
little evidence. The idea is that the
moon is full every month and women
menstruate monthly. Here's the thing:
Women's menstrual cycles actually vary
in length and timing — in some cases
greatly — with the average being about
every 28 days, while the lunar cycle is
quite set at 29.5 days. Still, there is one
study (of just 312 women), by
Winnifred B. Cutler in 1980, published
in the American Journal of Obstetrics &
Gynecology, that claims a connection.
Cutler found 40 percent of participants
had the onset of menstruation within
two weeks of the full moon (which means
60 percent didn't). If anyone can tell
me how this oft-cited study proves
anything, I'm all ears. Also, one should
be skeptical that in the intervening
three-plus decades, nobody seems to
have produced a study supporting
Cutler's claim.
Animals Gone Wild :
A pair of conflicting studies in the
British Medical Journal in 2001 leaves
room for further research. In one of
the studies, animal bites were found to
have sent twice as many British people
to the emergency room during full
moons compared with other days. But in
the other study, in Australia, dogs were
found to bite people with similar
frequency on any night. Some wild
animals do behave differently during a
full moon: For example, lions usually
hunt at night, but after a full moon,
they're more likely to hunt during the
day — likely to make up for the tough
going on a moonlit night.
Sleep Deprivation:
There's been a lot of research into this
topic. In the Journal of Affective
Disorders in 1999, researchers
suggested that before modern lighting,
"the moon was a significant source of
nocturnal illumination that affected
[the] sleep–wake cycle, tending to cause
sleep deprivation around the time of full
moon." They speculated that "this
partial sleep deprivation would have
been sufficient to induce mania/
hypomania in susceptible bipolar
patients and seizures in patients with
seizure disorders." When I first wrote
this story in 2009, I looked over these
oft-cited suggestions, scoured the
scientific literature, and could not find
where any of them had been tested or
verified with any numbers or rigorous
study of any kind. Since then, there
have been a few more studies on the
topic.
A small study in 2013 , of just 33
volunteer adults, found they slept less
during the full moon even when they
could not see the moon and were not
aware of the current lunar phase. The
researchers say the findings would need
to be replicated before they could be
considered reliable, however. Then in
2014, a broad review of sleep-moon
research, done by scientists at Max-
Plank Institute of Psychiatry, found no
statistically significant
correlation between the lunar cycle and
sleep.
More recently, research published in
March of 2016 , of 5,800 children age 9
to 11 in 12 different countries, found
they slept about 5 minutes less on nights
with a full moon. That's "unlikely to be
important" from a health perspective,
the researchers said, but it is
interesting. They speculate that the
brightness of the full moon may be the
reason, but with all the artificial light
around these days, they doubt that
suggestion.
Expect more small studies in the future
to suggest a link, and don't be
surprised if further broad scientific
reviews find the possible connections to
be shaky.
Myths persist
If one presumes that modern lighting
and mini-blinds have pretty much
eliminated the one plausible source of
human-related moon madness, why do
so many myths persist?
Several researchers point out one likely
answer: When strange things happen at
full moon, people notice the
"coincidental" big bright orb in the sky
and wonder. When strange things
happen during the rest of the month,
well, they're just considered strange,
and people don't tie them to celestial
events.
"If police and doctors are expecting
that full moon nights will be more
hectic, they may interpret an ordinary
night's traumas and crises as more
extreme than usual," explains our Bad
Science Columnist Benjamin Radford .
"Our expectations influence our
perceptions, and we look for evidence
that confirms our beliefs."
And that leads to this final note, which
is perhaps the biggest logical nail in the
coffin of the moon madness myths:
The highest tides occur not just at full
moon but also at new moon, when the
moon is between Earth and the sun (and
we cannot see the moon) and our planet
feels the combined gravitational effect
of these two objects. Yet nobody ever
claims any funny stuff related to the
new moon (except for the fact that
there is more beach pollution at full and
new moon ...).
Editor's Note: This article was originally
published in 2009. It was updated in
April 2016 to include new information
and the mention of the latest studies.
