Health care professionals are constantly warning us that too much sun exposure can significantly increase our risk for skin cancer, but it appears UV rays can affect our lifespan well before we’re old enough to catch a tan on the beach. A recent study conducted at the Norwegian University of Science and Technology has revealed that being born during a period of heightened solar activity can shorten our lifespan by over five years.

"This study is the first to emphasize the importance of UVR (ultraviolet radiation) in early life," the authors explained. "UVR is a global stressor with potential ecological impacts and the future levels of UVR are expected to increase due to climate change and variation in atmospheric ozone. Our results are thus highly relevant and contribute to a deeper knowledge of the consequences of UVR for animal life history, including human health."

Researchers gathered data using 8,662 people born in Norway between 1676 and 1878 while controlling for maternal effects and socioeconomic status. Individuals were categorized by poor and wealthy backgrounds as well as birth during periods of heightened solar activity, also known as solar maximum and minimal solar activity, also known as solar minimum. The sun’s 11-year cycle includes three years of heightened solar activity and eight years of minimal solar activity. Solar activity is gauged via sunspots and solar flares.

Norwegian individuals who were born during a period of heightened solar activity had a lifespan that was, on average, 5.2 years shorter than those who were born during a period of minimal solar activity. Infants born during a period of solar maximum were also at a higher risk to dying before the age of 2 compared to infants born during a period of solar minimum. Women from a poor socioeconomic background born during a period of heightened solar activity were also more likely to be interfile, but not women from a wealthy socioeconomic background.

"Our findings suggest that maternal exposure to solar activity during gestation can affect the fitness of female children," the authors added. "The effect of socio-economic status on the relationship between solar activity and fertility suggests that high-status pregnant women were better able to avoid the adverse effects of high solar activity."

The research team was unable to determine what exactly caused solar activity’s effect on human lifespan, but speculated it has something to do with the deterioration of B vitamin folate. Vitamin B9 folate or folic acid is recommended for any expecting mother to help prevent major birth defects that may impact their child’s brain and spine. Folic acid is essential to our body’s production of cells especially during pregnancy.

Source: Skjærvø G, Fossøy F, Røskaft E. Solar activity at birth predicted infant survival and women's fertility in historical Norway. Proceedings of the Royal Society B. 2014.