The next time you get annoyed at your spouse, you might want to grab something to eat. That's the take-home message from a new study that found marital hostility is at its highest when blood sugar is at its lowest.
Spouses of both genders jabbed more pins into a voodoo doll on evenings when their blood sugar was the lowest, according to the new study, published online Monday in the Proceedings of the National Academy of Sciences.
Lead researcher Brad Bushman of Ohio State University said his own marriage has improved since he took his study's advice: "When you discuss a sensitive topic with your spouse, you should do so over dinner, or better yet after dinner – but you should definitely not do it on an empty stomach."
Bushman and his colleagues paid $100 each to 107 married couples, found through public advertisements, to participate in the study.
To measure aggressiveness, each husband and wife was given a voodoo doll and 51 pins. They were told to check their blood glucose level before bed each night for three weeks, and to stick any number of pins into the doll, depending on how angry they were with their spouse that day. They didn't see each other's dolls.
After three weeks, the couples were invited back to the lab, placed in separate rooms and told to compete against each other to see who could press a computer button faster after a given command. The winner could blast the loser with a loud, ugly sound.
The spouses who stabbed their voodoo doll more freely also were more likely to turn up the volume on the punishing sounds, the study found. The results did not differ between couples who said their marriages were weak or strong, he said.
Angry people are more impulsive, more likely to lash out, both verbally and physically, said Bushman, adding that anger is the leading cause of homicide.
Ann Goebel-Fabbri, a psychologist with the Joslin Diabetes Institute in Boston, praised the creativity of the study but said she thinks the researchers went too far in suggesting that low blood sugar could lead to violence.
People with diabetes – who are prone to large swings in blood glucose – do complain about being moody, she said. But they are certainly not any more likely to be violent than the general population.
"There is no connection between diabetes and aggression," said Goebel-Fabbri, also an assistant professor at Harvard Medical School.
"I think the translation from voodoo doll and loud noise to domestic violence, I think is way overstating it," she said. "It would be lovely if we could solve the domestic violence problem by feeding people better, but…there's no data that would support that."