OPEN Molecular Psychiatry (2018) 23, 923–931 www.nature.com/mp ORIGINAL ARTICLE Bipolar mood cycles and lunar tidal cycles TA Wehr In 17 patients with rapid cycling bipolar disorder, time-series analyses detected synchronies between mood cycles and three lunar cycles that modulate the amplitude of the moon’s semi-diurnal gravimetric tides: the 14.8-day spring–neap cycle, the 13.7-day declination cycle and the 206-day cycle of perigee-syzygies (‘supermoons’). The analyses also revealed shifts among 1:2, 1:3, 2:3 and other modes of coupling of mood cycles to the two bi-weekly lunar cycles. These shifts appear to be responses to the conflicting demands of the mood cycles’ being entrained simultaneously to two different bi-weekly lunar cycles with slightly different periods. Measurements of circadian rhythms in body temperature suggest a biological mechanism through which transits of one of the moon’s semi-diurnal gravimetric tides might have driven the patients’ bipolar cycles, by periodically entraining the circadian pacemaker to its 24.84-h rhythm and altering the pacemaker’s phase-relationship to sleep in a manner that is known to cause switches from depression to mania. Molecular Psychiatry (2018) 23, 923–931; doi:10.1038/mp.2016.263; published online 24 January 2017 INTRODUCTION study addressed the question of whether periodicities correspond- The belief that the full moon can excite and disturb human ing to bi-weekly tidal cycles and perigee-syzygy cycles were also behavior is deeply rooted in culture, language and clinical lore, but present in these individuals’ courses of illness. It is worth noting it tends to be regarded as a myth by the scientific community that these types of lunar cycles do occur in other animals’ because it is not supported by epidemiological research.1,2 The behavior, and that lunar gravimetric cycles might not be affected failure to detect such an effect in the modern era, in which light by the light pollution that has obscured the moon’s luminance pollution has nearly extinguished lunar-phase variation in bright- cycle.6 ness of the night sky, does not necessarily mean that this effect was absent in previous centuries when nights were darker, Lunar tidal cycles however.3,4 In their natural habitats, other species of primates – generally do become more active at night under a full moon, and The spring neap cycle exerts its maximum effect on the ’ there are numerous examples of lunar cycles in other types of amplitude of the moon s gravimetric tides every 14.8 days, when animals.5,6 the sun, moon and earth are aligned at the full moon and at the In the present study, the author has taken an approach that new moon. The declination cycle exerts its maximum effect on differs from that of epidemiological studies, by looking for the tides, in one of the two daily tides, every 13.7 days, when the evidence of lunar periodicities in extensive longitudinal records declination of the moon’s orbit relative to the plane of the earth’s of course of illness in individual patients with rapid cycling equator causes the moon to reach the northern or southern bipolar disorder. This illness is characterized by a feature that extreme of its orbit. This cycle is responsible for the diurnal helps to delineate its course over time—a marked and inequality of the tides at many terrestrial locations. readily identifiable ‘switch process’, in which individuals shift The 206-day perigee-syzygy cycle exerts its maximum effect on abruptly from depression to mania, and vice versa, in the course of the tides every 206 days, when the sun, moon and earth are a single day.7,8 aligned at the full moon or the new moon, and the moon most The author undertook the study after examining the record of a nearly approaches the perigee of its elliptical orbit—an event patient (Patient 17) whose mood cycles exhibited a 35.5-day commonly referred to as a ‘supermoon.’ periodicity whose precision and stability over several years suggested that it might have arisen from a non-biological, clock- like source in the external environment. The fact that 35.5 days is MATERIALS AND METHODS the mean duration of double and triple multiples of two bi-weekly Patients lunar tidal cycles, that 1/35.4 days is the mean frequency of every Patients whose data are the focus of this report had forms of bipolar illness second and every third oscillation of one of those cycles, and that with the following characteristics: (1) a diagnosis of rapid cycling bipolar a recurring pattern in the mood cycles coincided with the 206-day disorder, according to criteria that prevailed at the time that they were lunar perigee-syzygy cycle suggested that the source of the 35.5- studied;9–11 (2) a circular course of illness in which sustained episodes of day periodicity might be the moon. mania of several weeks’ duration regularly alternated with sustained To investigate this possibility, the author conducted a retro- episodes of depression of similar duration; (3) a prominent ‘switch process’ spective study of 16 additional rapid cycling bipolar patients. The in which patients transitioned abruptly from one mood state to the other Intramural Research Program, National Institute of Mental Health, Bethesda, MD, USA. Correspondence: Dr TA Wehr, Scientist Emeritus, Intramural Research Program, National Institute of Mental Health, 35A Convent Drive, Suite GE 400, MSC 3747, Bethesda, MD 20892, USA. E-mail: [email protected] Received 22 July 2016; revised 14 November 2016; accepted 14 December 2016; published online 24 January 2017 Mood cycles and tidal cycles TA Wehr 924 Figure 1. Periodicities in 10 rapid cycling bipolar patients’ mood cycles were synchronous with every second, third, fourth, fifth or sixth oscillation of the moon’s 13.7-day declination tidal cycle. Figure shows results of χ2 periodogram analyses of longitudinal observations of the patients’ courses of illness. Statistically significant periodicities that correspond to each of the multiples of the declination cycle are labeled. A number of patients exhibited more than one type of synchrony during their courses of illness. over the course of a day or so;7,8 and (4) a frequency of 6 or more complete Bonferroni correction, but is still conservative. If the χ2 periodogram (mania+depression) cycles, that is, 12 or more affective episodes per year. analysis looks for a specific periodicity, as opposed to any periodicity, The patient group consisted of 6 men (Patients 1, 4, 6 and 8–10) and 11 corrections for multiple comparisons may not be necessary.16 women (Patients 2, 3, 5, 7 and 11–17) aged 21–69. Three patients were post-menopausal (Patients 3, 11 and 17). Patients lived in ambient light in urban environments in their homes or in hospital rooms with windows. All Data display patients had given written informed consent for their participation in Raster plots of bipolar cycles were constructed by dividing longitudinal studies that included longitudinal documentation of their course of illness, records of each time-series into segments equal to multiples of the and that were approved by the Institutional Review Board of the Intramural bi-weekly lunar tidal cycles (N = 16) or 35.5 days (N = 3), the period that was Research Program of the National Institute of Mental Health, except Patient prominent in the index patient’s mood cycles, and that is the mean of 8, who was seen in the author’s private practice and gave written informed double and triple multiples of the two types of bi-weekly lunar tidal cycles. consent for information concerning the course of his illness to be The segments were then displayed sequentially beneath one another, and published, and Patients 1 and 10, whose mood cycles were documented the resulting array was double-plotted to the right, to reveal the inherent by R. Gjessing in the 1920’s and 30’s in the pre-psychopharmacologcal era. continuity of the data and to facilitate visual inspection of courses of the The latter two patients were included in the analysis in order to explore the bipolar cycles across the plotting space. generalizability of methods and findings.9–12 Portions or all of 12 patients’ data were published previously without – – Supplementary Table 1 provides further information about patient reference to lunar cycles.8 12,13,17 20 Supplementary Table S2 provides characteristics. specific citations for each of these patients. Assessments RESULTS Clinical course was documented with calendar records of dates of switches back and forth between depression and mania that had been maintained The 17 patients were monitored for a combined total of 37.5 years, by patients themselves (Patients 3, 4, 6, 8 and 11), daily self-ratings of or 928 spring–neap cycles. mood (Patients 7, 9, 13 14 and 17) and by specially trained research nurses’ Onsets of the patients’ manic episodes were synchronous with behavioral daily ratings of depression and mania (Patients 1, 2, 5, 10, 12, 15 every second (N = 8), third (N = 11), fourth (N = 2) and/or sixth and 16).7,9,10,13 Research nurses also recorded the dates of Patients 12 and (N = 1) bi-weekly lunar tidal cycle (Figures 1 and 2). In most 16’s menses during the periods when their mood cycles were monitored. patients, onsets of mania were predominately synchronous with χ2 14,15 periodogram analyses were performed with each time-series. multiples of one of the two types of bi-weekly tidal cycles, the Periods comprising whole numbers of days were sampled between 10 and declination cycle (N = 9) (Figure 1) or the spring–neap cycle (N =8) 50 days (Patients 1–5, 7–10 and 12–17) or 20 and 100 days (Patients 6 and 11), and statistical significance for Q values was set at 0.05 (one-tailed).