How lunar cycles affect life
Moonstruck promises far more (especially in the subtitle) than it delivers. The claims for the influence of lunar cycles on life presented here are hedged around with terms like “subjective interpretation”, “equivocal” and “little hard evidence”. But full marks to the author for honesty, and he has produced a book which, while not exactly being a light read, contains many fascinating nuggets of information.
The rationale Ernest Naylor, who is Professor Emeritus in the School of Ocean Sciences at Bangor University, offers for producing his book now is that what he terms “the reality of the Moon” has been greatly enhanced by space probes and observations carried out on the Apollo missions, while at the same time its everyday (or every month) personal “reality” has become obscured to city dwellers. While the science of daily (circadian) rhythms of life has advanced over the past fifty years, he says, the study of Moon-related circatidal and circalunar rhythms has lagged behind.
But this highlights a problem with the book for the casual reader. The most pronounced lunar influences on life are indeed effected through tidal rhythms, and as an oceanographer this clearly fascinates Professor Naylor. But most of us have only a passing interest in the life cycles of crabs, marine worms and turtles, and would much rather learn about (or be entertained by stories of) lunar influences on human life. The snag being, there are precious few of them, they are mostly equivocal, subjective, and there is very little hard evidence to back them up.
All this, though comes right at the end of the book, after the compulsory nod at ancient myths and legends and a chapter of solid science in the form of the “Big Splash” model for the origin of the Moon, when a Mars-sized object collided with the young Earth, and the idea that life may have emerged in the tidal regions of our planet.
The intriguing nugget of information buried in the wealth of material about sea-dwellers that follows is that many creatures seem to possess an internal clock, which can be set by the tides, but operates semi-independently once set. The classic example is provided by a kind of worm which burrows in sandy beaches. The worms come to the surface at low tide, when the beach is uncovered, but burrow back into the sand just before the tide comes in. This can only be because their internal clock tells them the tide is due. Sure enough, when the are taken from the shore and put in tanks in the laboratory, where they experience no tides directly, they show the same rhythm of activity at first; but it gradually runs down. Then, if they are put back in their natural habitat the body clock gets re-set as they experience the ebb and flow of the tides once more.
It really is the ebb and flow that matters. There is no way that these influences can be arising from the direct gravitational influence of the Moon. As Naylor points out, “the gravitational pulls of the Moon and the Sun are so small that they affect the human body only by the weight equivalent of a bead of sweat or a human hair.” And worms proportionately.
So, skipping lightly past the crabs and turtles, what influence, if any, does the Moon have on what Naylor calls “the human condition”? Here we venture deep into the murky realms of equivocation and controversy. One study suggests that ruptures of aneurysms peak at the time of new Moon; another study finds no such evidence. Several published studies support the idea that the phases of the Moon influence sleep patterns in people. But then again, other researchers claim that this shows up in published data because similar studies which show no such effect did not get published.
In fact, when it comes to lunar influences on the human condition Naylor is much more convincing when dismissing alleged correlation than when trying to bolster them. Contrary to a popular belief, emergency admissions to hospital do not show any correlation with the phases of the Moon, suicides do not follow the lunar cycle, and epileptic seizures are not influenced by the Moon. In 1982, a study showed that “there was no significant correlation between the daily or monthly phase of the Moon and human libido, thus shattering another myth concerning the Moon and the human condition.” The author is reduced to the rather plaintive conclusion that “perhaps there may yet prove to be something behind the folklore concerning human behaviour and the Moon”; then again, perhaps not.
The biggest puzzle about this book is why (and how) it should appear under the imprint of Oxford University Press. It would be quite at home with a small press, or in this day and age as a self-published print on demand title. That might also have made it possible to offer the title at a more sensible price for what is a quite slim volume with a somewhat limited audience. But what do I know. I only write books, I don’t publish them!
John Gribbin is a Visiting Fellow in Astronomy at the University of Sussex. His latest book, 13.8, describes the quest to determine the age of the Universe and the stars it contains.