Frequency of contact with community-based psychiatric services and the lunar cycle: a 10-year case-register study.

The relationship between the lunar cycle and the frequency of contact with community-based psychiatric services was assessed using the South Verona Psychiatric Case Register data. For each day of the study period (January 1982-December 1991) we recorded the number of contacts made by South Verona residents with psychiatric services and the corresponding day of the lunar cycle. First, the synodic month was divided into four interval phases (usually called new moon, first quarter, full moon and third quarter), and interphase differences in the mean number of contacts were tested using one-way analysis of variance. Second. the null hypothesis of no relationship between the lunar cycle and the frequency of contact with psychiatric services was tested against the alternative hypothesis of a sinusoidal distribution according to the lunar phase. The average number of contacts with psychiatric services on each day of the lunar cycle over the 10-year period was obtained and a sine-wave curve was fitted to the data. Both for total and drop-in contacts, no significant differences in mean number of contacts were found between the four interval phases of the synodic month (new moon, first quarter, full moon and third quarter). Similarly, no significant results were found by setting the expected surge in consultations at 1-3 days after the full moon and the period of the sine-wave curve equal to 30 days. When the period of the sine-wave curve was allowed to vary in order to fit the data best, none of the statistical tests reached the level of significance required to dismiss the possibility of false-positive results. These findings did not support the theory that a relationship exists between the lunar cycle and the frequency of contact with community-based psychiatric services.