Couples fight. That's normal. But if you and your spouse are constantly fighting, there may be scientific cause to it. One psychologists thinks it might have to do with blood sugar. How in the world did he even relate blood sugar with couples fighting?

Brad Bushman works at Ohio State University at Columbus, and he studies the role of blood sugar levels in behavior. He hypothesized a couple years ago that low glucose levels in the blood might be causing spouses to behave more "aggressively" toward each other.

So how do you measure the relationship of an angry person to their blood glucose levels? In Science, Gisela Telis writes:
[Bushman] and colleagues at the University of Kentucky and the University of North Carolina recruited 107 married couples and equipped them with blood glucose meters, voodoo dolls, and 51 pins to record their glucose and anger levels over time.

For 21 days, the couples used the meters to measure their glucose levels each morning before breakfast and each evening before bed. They also assessed how angry they were at their spouse at the end of each day, by recording how many of the 51 pins they stuck into their voodoo dolls just before bed when their partner wasn't looking. After 21 days, the couples were invited into the lab. There, they played a computer game that allowed them to blast their spouse with an unpleasant noise—a mixture of fingernails scratching a chalkboard, ambulance sirens, and dentist drills—as loudly and for as long as he or she wanted, as a proxy for their willingness to act aggressively and make their partner suffer.
According to Telis, they found that "spouses with lower evening glucose levels showed more anger and aggression toward their partners." People who were in the 25th percentile of glucose levels were roughly twice as angry compared to those in the upper 25th percentile.

They conducted an experiment where they found those who were more angry stuck more pins in a voodoo doll than those who weren't.

But here's the thing. The study didn't ask the subjects if they had been eating or drinking. Alcohol can lower glucose levels, but also raise aggression levels.

Still, it doesn't hurt to experiment, without your partner knowing. Give them something to raise the glucose levels in their blood sugar. See if there's more harmony.

Read the full scientific study in the Proceedings of the National Academy of Sciences