ҹ1000

Blame it on the moonlight

IN The Wolf Man, Larry Talbot knows he’s just impossible at certain
times of the month. In one famous scene from this 1941 Hollywood classic, he
catches sight of his palms and howls in horror. They’re hairy—a sure sign
there’s a full Moon and he’s turning into a werewolf.

OK, so it’s just a silly movie. All the same, lots of people harbour a
sneaking suspicion that the Moon really can influence how we behave—though
probably not to the extent of turning us into wolves. Numerous studies have
looked for a relationship between the Moon and behaviour and many have found
one. Crime, violence and accidents seem to be more common when the Moon is full.
Women appear more likely to give birth, especially if they’re having twins.

Mundane behaviours such as eating and drinking have also been linked to the
phases of the Moon. Late last year researchers at British Telecom even found
that its customers were more likely to surf the Internet during a full Moon.
Lunacy, it seems, is an idea that just won’t go away. So is there anything in
it?

Belief in the Moon’s power to unsettle and even disrupt human behaviour
stretches back to antiquity—the word lunacy derives from Luna, the Roman
goddess of the Moon—and persisted well into Victorian times, when “lunacy
acts” regulated the treatment of the insane. In the 1830s, inmates of London’s
notorious lunatic asylum Bedlam were bound, chained and flogged as the full Moon
approached, as a precautionary measure against “increased turbulence”.

The rise of modern science made lunacy theories unfashionable, yet in recent
years they have made a comeback. With the rise of chronobiology—the study
of the biological clocks ticking away in virtually every organism—has come
a new-found interest in periodic changes in behaviour, some of which might just
be linked to the Moon’s 29.5-day cycle.

Over the past 20 years, researchers looking for lunar rhythms among people
have found them all over the place. Calls to crisis centres, absenteeism, heart
attacks and mental hospital admissions have all been linked to phases of the
Moon. Rape, robbery, assault, theft, domestic violence, suicide attempts,
poisonings, drunkenness and disorderly conduct also appear to become more
prevalent in the two or three days around a full Moon. A study in 1995 by
psychologists at Georgia State University in Atlanta found that people ate more
food but drank less alcohol when the Moon was full. In another study from 1998,
a trio of Italian mathematicians looked at the timing of births. They reported
“significant clustering” of deliveries in the first or second day after the full
Moon. The effect was particularly strong in mothers who had already had at least
one child, or who gave birth to twins or triplets.

What’s more, survey after survey has revealed an entrenched belief among
healthcare workers—the people who mop up after madness descends—in
the power of the Moon. In the US, four out of five mental-health professionals
and two-thirds of emergency doctors believe that human behaviour is influenced
by the Moon.

The latest piece of evidence suggests that the lunar cycle even influences
our use of technology. Last year, researchers at British Telecom noticed a
29-day cycle of peaks and troughs in network traffic. “Just out of curiosity,”
says Stewart Davies of BT, “we matched the cycle against the phases of the
Moon.” The cycles coincided. In the seven days before a full Moon, people spent
more time talking on the phone or surfing the Internet than at other times of
the month. If this apparent link stands up to scrutiny, says Davies, BT could
soon be managing its network according to the phases of the Moon.

Feeling phased

If a sober, blue-chip company like BT is thinking about changing its business
practices to account for lunacy, surely there must be something in it? Not
necessarily. There are plenty of reasons to believe that the whole idea is pure
moonshine.

For every study that finds a correlation, there’s another that doesn’t.
Researchers have repeatedly looked for a link between the phases of the Moon and
the onset of mania and depression. Nobody has found one. What’s more, positive
correlations are often unrepeatable. Car accidents, emergency room admissions,
alcohol intake, drug overdoses and the timing of births, for example, have all
been shown to be unrelated to the phases of Moon—flatly contradicting
earlier studies. Add to this the fact that few researchers bother to publish
negative results, and the lunacy theory starts to look flimsy. In all
likelihood, positive results are freak events.

And anyway, how might the Moon exert an influence over the way we behave? No
one knows, and the ideas that have been put forward are barely plausible.

Take the “biological tides” theory. The idea is that since our bodies are 80
per cent water, the Moon must “pull” on our bodily fluids just as it does on the
oceans. Sounds dubious, and it is. In 1995, Daniel Myers of the University of
Pittsburgh School of Dental Medicine launched a scathing attack on this idea in
The Journal of Emergency Medicine. He points out that the gravitational pull of
the Moon has little to do with whether it’s full or not. Peaks happen twice a
day regardless of the Moon’s phase. Lunar gravity is minuscule compared with the
gravitational effects we experience in daily life. “The acceleration due to
walking would create gravitational effects of far greater magnitude than those
caused by the Moon and Sun combined,” he says.

Another idea is that the Moon influences the weather, which in turn makes us
act strangely. There is some support for this—a US National Weather
Service study in the 1970s found there was 10 per cent more rain in the days
after a new or full Moon. And wet weather makes people gloomy. “It could be a
case of rainy days and Mondays always getting me down,” says George Masterton, a
psychiatrist at the Edinburgh Royal Infirmary, who has found that people are
slightly more likely to attempt suicide during full or new Moons.

But if there is an effect, it’s an indirect one. According to Britain’s
meteorological office in Bracknell, Berkshire, there’s no direct link between
the phases of the Moon and the weather. Rather, any apparent effect is caused by
the tides’ subtle influence over the weather—fogs rolling in from the sea
at high tide, for example. But once again the effect is small.

Can we blame it on the moonlight? Well-known neural pathways link the eye to
the body’s biological clock in the hypothalamus and pineal gland—the
source of the jet-lag hormone melatonin—as work by Josephine Arendt at the
University of Surrey and others has established. The trouble, says Arendt, is
that moonlight itself is probably far too faint to influence these timekeeping
mechanisms.

If that wasn’t bad enough for the believers, there are also doubts as to the
validity of the research. Back in 1985, psychologists James Rotton of Florida
International University in Miami and Ivan Kelly of the University of
Saskatchewan, Canada, examined 37 lunacy studies. They concluded that most were
beset by methodological problems. When they corrected for these, all those
intriguing relationships between human behaviour and phases of the Moon
vanished.

Lunacy, then, doesn’t stand up to scrutiny. There’s too much negative
evidence, too many methodological errors and no plausible mechanism. A victory
for the sceptics, but one that still leaves one nagging question. Why is the
lunar myth so persistent?

Psychiatrist Charles Raison of the University of California at Los Angeles
believes he has the answer. He argues that the lunacy myth is a “cultural
fossil”—a memory of a time when the Moon really did have a
behaviour-altering power that it has since lost.

What’s changed in modern times, he says, is the importance of the Moon as a
source of nocturnal illumination. In the days before gas lamps and electric
lights, when candles were an expensive luxury, a moonlit night gave people an
opportunity to do all sorts of things—plough, hunt or travel, for
instance. In the three days around the full Moon, lunar light is 12 times
stronger than at half full. Overall, people stayed up later and slept less
during the full Moon than at other times of the month, Raison argues.

Here at last is a plausible link between the Moon and behaviour. Sleep
deprivation over a single night can induce mania, Raison says, even in healthy
people. Epileptic fits can also be provoked by sleep deprivation, and may once
have been blamed on the malign influence of the Moon. Raison’s theory also
neatly explains why lunar influences are so elusive today. He suspects that
artificial lighting swamps any effects the Moon used to exert on the way we
behave.

There is already evidence that artificial lighting in towns and cities
suppresses changes in circadian rhythms, including the release of melatonin.
Thomas Wehr and his colleagues at the National Institute of Mental ҹ1000 in
Bethesda, Maryland, found that men living in Washington DC showed none of the
predicted seasonal changes in body chemistry. The highly lit urban environment
blocks the body’s response to seasonal changes in the hours of daylight. If
artificial lighting can do that, it can surely swamp any impact of moonlight.
Even the brightest full Moon can’t compete with sitting near a 100-watt light
bulb.

It’s a neat idea, experts in human biorhythms agree. “I’ve worked in
Botswana, in a place where there was no mains electricity,” says nutritionist
Linda Morgan of the University of Surrey. “The difference in activity cycles
when the Moon was full was very marked. People were out and about visiting
people well into the night. The whole fabric of society, the feasts and such
like, was organised around full Moons.”

Raison’s idea is even testable. Researchers should look for the effects of
the Moon in societies where it still influences sleep-wake cycles, he suggests.
Native Americans living traditional lifestyles in the south-western US might be
ideal for such a study, he says. There we might find the ancient belief in the
power of the Moon vindicated at last—and settle a question as old as
lunacy itself.

Humans are not the only ones supposedly under the Moon’s influence. Some
people think animals are lunatics too.

In January, The Veterinary Record published a letter from Michael
Gilmore, a vet working in the Dordogne, about a widespread belief in France that
the full Moon makes horses more prone to colic. He wanted to know if similar
beliefs were prevalent in Britain and Ireland.

In reply, Fergal Hennessy, a vet in County Clare, reported that the Moon had
a huge influence on his working life. Folk traditions hold that the waxing Moon
promotes healthy growth in animals and is the best time for calving. It is also
a good time for planting seeds and cutting hair. Many of Hennessy’s clients
would not undertake routine chores, such as dehorning or castrating livestock,
if the Moon was waxing—they feared the animals would bleed excessively.
But such chores would be tackled with gusto while the Moon was waning. Local
people also believed that weeding, cutting corns or charming warts were best
done by a waning Moon.

There is some evidence that animal behaviour is influenced by the Moon. Last
year, Chanchal Bhattacharjee, a casualty doctor at the Bradford Royal Infirmary,
published a paper in the British Medical Journal examining the timing
of 1621 bite injuries from animals—inflicted mostly by dogs, but also
cats, rats and horses—over three years. To his surprise, he found that the
number of victims rose swiftly a few days before a full Moon and peaked sharply
on the day of the full Moon itself.

But as always seems to be the case with lunacy research, there is also
evidence to the contrary. Alongside Bhattacharjee’s paper, the BMJ
published a study by Simon Chapman of the department of public health at the
University of Sydney. His conclusion was that admissions for dog bites are no
more frequent during a full Moon than at any other time.

Animal crackers

  • Further reading: “The Moon and madness reconsidered” by Charles Raison, Haven
    Klein and Morgan Steckler, The Journal of Affective Disorders, vol 53, p 99
    (1999)
  • “Much ado about the full Moon: a meta-analysis of lunar-lunacy research” by
    James Rotton and Ivan Kelly, Psychological Bulletin, vol 97, p 286 (1985)
  • See a movie of the lunar cycle at http://aa.usno.navy.mil/faq/docs/moon_phases.html

More from New Scientist

Explore the latest news, articles and features