As evidenced by the research highlighted in this essay, the idea that the activities of organisms are regtdated by internal timing mechanisms that are synchronized by environmental factors has been well established by scholarly investigations. Nevertheless, many popular notiorts concerning biological rhythms are still plentiful, often with little evidence to support them. Indeed, one such popular warping of chronobiology involves the use of what have been termed ‘‘biorhythms” by mystics and astrologers to forecast good or bad days or specific events in an individual’s life, based solely on knowing the individual’s birthday. However, as noted by Alain Reinberg, director of research, National Center of Scientific Research (CNRS), Paris, France, and Michael H. Smolensky, associate professor of environmental sciences, University of Texas Health Sciences Center, Houston, this is a “completely invalid and unacceptable definition” of the term, rendering its use by chronobiologists infrequent.34
Other popular beliefs surround rhythmic variations based on the phases of the moon. Although lunar phases are indeed correlated with some biological periodicities, such as menstruation in womenss and metabolic and hormonal changes in srdmon that regulate the fishes’ reproductive process,35 other associations between the moon and biologic events are less concrete.
For instance, one notion involves an association between the moon and fertility or romance. Several studies have found a weak, but definite, positive correlation between the phases of the moon and birthrates- i .e., births increase as the moon approaches fullness, peak when the moon is till, and deehtte thereafter, with the bottom of the curve occurring during the new-moon phase.37-42 The explanation has been offered that, if menstrual cycles are indeed in tune with the phases of the moon, the time of the ~ moon may represent a peak in fertility, thus acmunting for a peak in birthrates at about the same time some nine months hence;41 however, other studies have found no or even a negative correlation between the phases of the moon and birthrates .43
The moon has also been tentatively linked to various types of abnormal behavior44-46 (accounting for the origin of the word ‘‘lunacy’‘), inciudlng suicide.47 Indeed, a number of studies have found that various mental disturbances, partieukdy depression, exhibit some form of Periodicity;48, 49 some such disorders even seem to be caused by disrupted or abnormal biological rhythms50-52 and can be treated by “adjusting” the individual’s rhythm through the use of a synchronizer, such as light.53-54 However, it should be noted that there are difficulties inherent in trying to separate the effects of a possible internal clock on behavior from the external, social cues that occur in a definite rhythm. For instance, an annual rise in the suicide rate is experienced around the Christmas and New Year’s holidays in many countries, but this is more likely due to excessive alcohol consumption and cases of depression brought on or exacerbated by the holidays than by disorders akin to SAD.55
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