Premium
Month of birth and mood seasonality: A comparison between countries in the northern and southern hemispheres
Author(s) -
Tonetti Lorenzo,
Milfont Taciano L.,
Tilyard Benjamin A.,
Natale Vincenzo
Publication year - 2013
Publication title -
psychiatry and clinical neurosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.609
H-Index - 74
eISSN - 1440-1819
pISSN - 1323-1316
DOI - 10.1111/pcn.12036
Subject(s) - seasonality , season of birth , mood , photoperiodism , demography , southern hemisphere , medicine , biology , psychiatry , ecology , sociology
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: I taly (northern hemisphere) and N ew Z ealand (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 S easonal P attern A ssessment Q uestionnaire was administered to 1514 young adults (1088 women, 426 men; 1027 Italians, 487 N ew Z ealanders), with ages ranging from 18 to 34 years. The G lobal S easonality S core, which is a measure of mood seasonality, was calculated from the S easonal P attern A ssessment Q uestionnaire. Results A significant overall month‐of‐birth effect was observed on the G lobal S easonality S core, but only for men. Men born in A pril and A ugust (corresponding in I taly to a long photoperiod, in N ew Z ealand to a short photoperiod) had higher mood seasonality than those born in F ebruary, 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.