Astrologers and other spiritual types are typically the only people to believe in a connection between a person's birthday and their personality. But according to a recent study, there's scientific evidence that indeed, the season of your birth may have some impact on who you are.
Researchers from Semmelweis University in Budapest studied a sample of 366 Hungarian university students, finding that people born in the summer were more likely to experience frequent mood swings as adults. People born in the winter, however, were less likely to develop irritable personalities. Spring birthdays were more likely to yield "excessively positive" temperaments, while people born in autumn were less likely to be depressive.
“Biochemical studies have shown that the season in which you are born has an influence on certain monoamine neurotransmitters, such as dopamine and serotonin, which is detectable even in adult life," lead researcher Xenia Gonda, an assistant professor at the university, said in a written statement. "This led us to believe that birth season may have a longer-lasting effect."
These neurotransmitters play a role in the regulation of cognitive processes like emotion and arousal, contributing to mood, so the researchers believe they might influence the development of certain types of temperaments. But since this initial study just included a survey and didn't follow participants over time, more research is needed to determine precisely how and to what extent there is a connection between the two factors.
“We can’t yet say anything about the mechanisms involved," Gonda acknowledged in the statement. "What we are now looking at is to see if there are genetic markers which are related to season of birth and mood disorder."
Of course, certain early environmental factors that are related to season -- such as available food and nutrients, the mother's level of physical activity, temperature and environmental pathogens -- may also affect temperament in later life, Gonda said.
"[Around] 400 subjects is a relatively small sample size, so the findings may be chance," Sreeram Ramagopalan, a neuroscience lecturer at Oxford University who was not involved with this study, but has studied the effects of birth season on mental disorders, told The Huffington Post. “Nevertheless, for some disorders (e.g. schizophrenia), a convincing season of birth effect has been found. Potential hypotheses to explain these findings are either maternal infections or maternal vitamin D levels, both of which are known to vary seasonally.”
"Birth season is a proxy for several environmental effects which are in action during gestation and shortly after birth," Gonda explained in an email to The Huffington Post. "[These] periods are crucial for the development of the central nervous system."
Here's how the findings break down by season:
- Summer: Higher instances of "cyclothymic temperament," characterized by quick, frequent swings between sad and cheerful moods.
- Spring & Summer: Higher instances of "hyperthymic temperament," a personality tendency to be overly positive.
- Winter: Decreased likelihood of developing irritable temperament, as compared with those born at other times of the year.
- Autumn: Significantly lower tendency towards depressive temperament than those born in winter.
It's important to note that the study was conducted in Hungary -- which has a climate of warm, dry summers and cold winters -- and that seasonal differences in environmental factors may not be as important in areas closer to the equator.
At this stage, the findings shouldn't be taken as conclusive, and further research is needed to distinguish between correlation and causality. The findings were recently presented at the European College of Neuropsychopharmacology Congress in Berlin.