The moon has always been a source of inspiration for popular legends. In our collection we find some very sophisticated, such as men who transform into a wolf when there is a full moon, and others less fanciful, such as those related to fertility.
The fact that the lunar cycle lasts about the same as the menstrual cycle has led the confirmation biases to do the rest. However, today it seems that there is no relationship between a certain moon phase and a increased frequency of deliveries or pregnancies.
The belief that the full moon can disrupt human behavior is also deeply ingrained in culture, language, and popular wisdom. Not in vain, the Dictionary of the Spanish Language collects the term “lunatic” and defines it as “who suffers madness, not continuous, but at intervals”. However, despite the fact that throughout history the full moon has been blamed for the worsening of different psychiatric disorders, the truth is that most of the evidence points, to this day, that the moon is innocent .
Some authors consider, however, that current light pollution could mask the light reflected by the full moon, preventing its effects from being detected today (with some exception). They do not rule out that in previous centuries, without electricity, that natural night light could alter people’s spirits in some way.
In fact, recent work has shown certain synchrony between mood swings in patients with rapid cycling bipolar disorder and lunar cycles. The author of this study suggests that a part of the patients’ circadian system (the internal clock) would be synchronized to lunar days (24.8 hours), while other components of the clock would remain synchronized to 24-hour solar days.
Desynchronization between biological rhythms, including sleep, could be behind the transition from depressive to manic in these patients.
How do we sleep with a full moon?
Although there is still controversy in this matter, The truth is that some works have been published in which it has been observed that sleep latency, that is, the time it takes us to fall asleep, increases in the days before the full moon. In addition, deep sleep, that of slow waves, could be reduced on those days.
Already in 2013, a job published in Current Biology and led by Christian Cajochen pointed to the effect of the lunar phases on aspects of sleep evaluated by electroencephalography. Volunteers slept 20 minutes less on average and had 30% less deep sleep in the days leading up to the full moon.
The researchers also highlighted an important aspect of the study: its retrospective nature. No person involved in the data collection process was aware that it was about evaluating the possible effect of the lunar phases. They evaluated sleep with a totally different objective, and it occurred to them to analyze this factor years later, having a drink on a full moon night. That eliminated any bias at a stroke, and also the possible placebo / nocebo effect.
Earlier this year, a team of researchers including Leandro Casiraghi and Horacio de la Iglesia published a job in Science Advances confirming these results. In this case, they did so by ambulatory monitoring (with a wristband device) of Argentine indigenous tribes (with and without access to electric light), and of a highly industrialized US population. In all three situations, the results were similar: the full moon delayed bedtime and shortened sleep duration.
Is the light to blame?
But what aspect of the full moon makes us (supposedly) sleep less? It is clear that on full moon nights there is more light, especially if we do not mask it with electric light. However, in both studies the effect of light reflected by the moon was ruled out.
In the first case, because the volunteers’ sleep was recorded in controlled laboratory conditions (without receiving light from outside). In the second, because both the tribe without access to electricity (with less light pollution and greater potential influence of moonlight) and the tribe with access to electricity and the industrialized population showed similar effects.
It is not clear if it is an endogenous rhythm that we maintain or if our organism is sensitive to the effect of gravity exerted by the moon in its different phases. If it were the latter, Casiraghi and his collaborators explain that, although the gravitational force would be the same on a full moon and a new moon, each one occurs at different times.
Thus, the full moon is the only one that would exert this effect during the night, when we sleep. Other authors, however, rule out that the gravitational force of the moon may have an effect on masses as small as our body.
In any case, the possible stimulating effect of the full moon would be the result of the adaptive advantage of being more active on those nights when there was more natural light to see around us.
Like everything that surrounds the moon, its effect on sleep is also a mysterious matter … for now. Little by little science will continue to make its way.
Until then, if you’re feeling awkward on nights with a full moon, fear not: it may just take a little longer for you to fall asleep.
Maria Angeles Bonmatí Carrión, CIBERFES postdoctoral researcher and UMU associate professor, University of Murcia
This article was originally published on The Conversation. read the original.
Reference-www.eleconomista.com.mx