Mania and seasonality in the southern hemisphere

Admissions for mania over a 9-year period in New Zealand were analysed, including data from four separate regions spanning nine degrees in latitude. A spring/summer peak of admissions for mania was found. The four regions showed marked, unexpected variability in seasonality. Regression analyses were performed to test the association of admissions for mania, in the month of admission and the previous month, with mean daily temperature, day length, hours of bright sunshine and mean relative humidity plus the rate of change of each of these variables.