Aims A previous study has reported a significant month‐of‐birth effect on mood seasonality in the northern hemisphere. Higher mood seasonality was observed for university students born during spring or summer months (long photoperiod) compared to those born during autumn or winter months (short photoperiod). The aim of this study was to test the hypothesized photoperiod effect by comparing the correlation between month of birth and mood seasonality in two countries located at the opposite poles of the terrestrial globe: Italy (northern hemisphere) and New Zealand (southern hemisphere). On the basis of the photoperiod‐at‐birth hypothesis, we expected to find higher mood seasonality among individuals born in months with longer photoperiods in both countries. Methods The Seasonal Pattern Assessment Questionnaire was administered to 1514 young adults (1088 women, 426 men; 1027 Italians, 487 New Zealanders), with ages ranging from 18 to 34 years. The Global Seasonality Score, which is a measure of mood seasonality, was calculated from the Seasonal Pattern Assessment Questionnaire. Results A significant overall month‐of‐birth effect was observed on the Global Seasonality Score, but only for men. Men born in April and August (corresponding in Italy to a long photoperiod, in New Zealand to a short photoperiod) had higher mood seasonality than those born in February, regardless of country. Conclusions A significant month‐of‐birth effect was found on mood seasonality, but results do not support the hypothesis based on the photoperiod effect.

Brief communication Female gender but not season of birth is associated with mood seasonality in a near-equatorial Brazilian cityGreater mood seasonality has been observed for individuals born during spring/summer months than those born during autumn/winter months. Expanding past research to the Southern Hemisphere, in this study we examine the influence of season of birth on mood seasonality in a sample of 1,247 healthy young Brazilians. method: The Seasonal Pattern Assessment Questionnaire was used to compute a global seasonality score as a measure of mood seasonality in a cross-sectional study. results: Analysis of covariance was conducted to examine the effects of month of birth and gender on mood seasonality, with age entered as a covariate. A main effect of gender was observed, F (1, 1197) = 17.86, p < .01; partial Eta-squared = .02, with mood seasonality being higher for females (M = 8) than for males (M = 7). Contradicting previous findings, no significant main effect for month of birth was observed, F (1, 1197) = 0.65, p > .05. conclusion: The unexpected finding is tentatively explained by differences in geographic location and weather fluctuations between the sampling location in Brazil and other countries where season of birth has been found to influence mood seasonality. Additional studies with larger samples from the Southern Hemisphere are necessary to shed additional light on the possible significant influence of season of birth on mood.reSumo objetivo: Estudos realizados principalmente em países do Hemisfério Norte têm demonstrado que indivíduos nascidos durante os meses de primavera/verão tendem a apresentar maiores alterações sazonais do humor do que aqueles nascidos durante os meses de outono/inverno. Expandindo essas pesquisas para o Hemisfério Sul, o presente estudo examinou a relação entre época do nascimento e a flutuação sazonal do humor em uma amostra de 1.247 jovens brasileiros saudáveis de João Pessoa, Paraíba. método: Uma versão traduzida do Seasonal Pattern Assessment Questionnaire (SPAQ) foi utilizada para calcular uma pontuação