"Although there is no widely accepted explanation for this finding, one theory is that loneliness increases stress, which damages health," according to the National Geographic site.

The quiz also points out that stress is a powerful force. It can stunt growth or make hair fall out--but also can dull pain.

IT'S PRIMAL

In a fascinating short film posted online, Stanford University neurobiologist Robert Sapolsky explains that the body's responses to stress are designed to save our lives.

"If you're a normal mammal, what stress is about is three minutes of screaming terror on the savannah, after which either it's over with, or you're over with," Sapolsky said as the film showed a lion chasing a zebra.

The problem is, many humans have the same "fight or flight" stress response to things like fear of speaking in public or work deadlines as if they were literally running for their lives.

The hormones released during that stress response are what lead to increased risk of heart attack, mental health problems and a host of health issues, from infertility to fatigue to frequent colds.

And while no one can completely eliminate stress, sometimes simply hitting the internal reset button can make a world of difference.

"Typically, when people are under stress, they revert to strategies that are most familiar, whether some of those are the most effective or not," said LaFave, pointing to excessive drinking or snapping at the kids.

Another common fallback is stress-related overeating, which can contribute to holiday weight gain. Local dietitian Nancy Farrell said you can tackle that bugaboo with a few smart strategies such as eating only at the kitchen or dining room table (no scarfing a burger in the car or at your desk).

Also, aim for at least seven hours of sleep nightly, drink plenty of water, watch your caffeine intake, take a daily multivitamin and try to stick to a daily exercise plan.

HOLIDAY STRESS

Stress responses such as overeating or heightened irritability can be compounded during the holidays, which have the reputation for being "the most wonderful time of the year."

"Part of the expectation is everyone wants to see everyone they love," and that can mean four sets of parents for married couples with parents who have divorced and remarried, LaFave said.