Figure 6.

Five instances of synchrony of every second mood cycle with every third bi-weekly lunar cycle. Raster double plots of bipolar cycles (a) and courses of manic episodes across the plotting space (b), are shown as described for Figures 4 and 5. The occurrence of 2:3 synchrony of mood cycles with lunar cycles in Patients 13 and 14 is confirmed by χ² periodogram analyses (c). As a reference, the duration of 1.5, 2 and 3 spring–neap cycles (22.1, 29.5 and 44.3 days, respectively) are shown above the periodograms. At different times, Patient 13’s mood cycles exhibited all three modes of synchrony with the lunar cycle (b, c). Patient 14’s periodogram and the first of Patient 13’s three periodograms show the first harmonic at circa 22.1 days, which is the fundamental period of the mood cycle, together with the second harmonic at circa 44.3 days, which is the period of recurrence of every third bi-weekly lunar cycle. Synchrony of every second mood cycle with every third lunar spring–neap cycle is evident in a linear plot of the time-series of Patient 14’s daily self-ratings of mood, in which times of full and new moons are indicated by open and closed circles, respectively (d).