Objective: Earlier general population studies have shown that novelty seeking (NS) of the Temperament and Character Inventory (TCI) of personality is lower for persons born in winter compared to those born in summer, particularly for women. Here, we investigate if this result can be replicated in another population.
Method: The Northern Finland 1966 Birth Cohort, comprising 4968 subjects (2725 women, 2243 men), was investigated with regard to the temperament dimensions of the TCI and the season of birth.
Results: Novelty seeking and reward dependence (RD) showed significant variations according to the month of birth. We found that women born during winter have significantly lower levels of NS compared to women born during summer, with a minimum for the birth month November and maximum for May. These results are similar to those found in a previous Swedish study. Furthermore, our study showed that men born during spring had significantly lower mean scores of RD compared to men born during autumn, with a minimum for birth month March. This was in contrast to the Swedish study, where the minimum of RD was obtained for the birth month December.
Conclusion: Women born in winter have lower NS as adults compared to women born in summer. Because NS is modulated by dopamine, this study gives further support to the studies in the literature that show that dopamine turnover for those born in winter is higher than for those born in summer.