Could low blood-sugar levels contribute to spousal anger?
Previous studies have suggested that low blood sugar (glucose) may play a role in aggression by undermining self-control. When glucose levels are low, people tend to have more difficulty paying attention, regulating their emotions and resisting aggressive impulses.
Research has also found that people struggle more with self-control as the day progresses, perhaps because glucose breaks down into energy less efficiently later in the day.
For the new study, a team of researchers from Ohio State University, the University of Kentucky and the University of North Carolina decided to investigate the hypothesis that low glucose levels are associated with aggressive tendencies among intimate partners.
What they discovered suggests that couples may want to head to the kitchen pantry the next time they find themselves on the verge of a marital spat.
For the study, the researchers recruited 107 heterosexual couples who had been married an average of 12 years. The participants had a mean age of 35, and most (78 percent) were white.
Each participant was equipped with a blood-glucose meter and a voodoo doll with 51 pins. For 21 days, the participants measured their blood-glucose levels twice a day: each morning before breakfast and each evening before bed. The participants were also instructed to stick pins in the voodoo doll each evening — “depending how angry you are with your spouse” — and then record that number. They were told to do this activity alone, without their spouses present. (Believe it or not, this method of measuring aggression has been validated in other studies.)
After the 21 days, the couples were brought into a laboratory for the second part of the study. They donned headphones and played a computer game in direct competition with their spouse. The game involved pressing a button faster than the other player when a square on the computer screen turned red. The “winner” could then blast his or her spouse with a loud, unpleasant noise through the headphones — sounds that included ambulance sirens, dentist drills, and fingernails scratching on a chalkboard. (Although the participants did not know it, they were actually playing against a computer, not their spouse, so no one’s eardrums got harmed.)
Both the at-home and the in-the-lab experiments found that blood-glucose levels predicted how angry participants would be with their spouses. In the voodoo-doll experiment, the lower the participants’ evening blood-glucose levels, the greater the number of pins they stuck in the dolls.
“Those in the lower 25% stuck more than twice as many pins in the doll as those in the upper 25% of glucose,” stated Brad Bushman, the study’s lead author and professor of communication and psychology at Ohio State University, in an e-mail exchange with MinnPost.
That finding held even after the researchers made adjustments for the couples’ marital satisfaction.
In the computer-game experiment, the same was true. Individuals with lower blood-glucose levels played the game more aggressively. They were significantly more likely to send their spouses long, loud blasts of unpleasant noises through the headphones whenever they won a round of the game.
Not the only factor
Of course, a low blood-glucose level isn’t the only — or even the most important — factor involved in anger and aggression within relationships, certainly not as potentially important as alcohol use, for example.
Still, Bushman has some advice for couples who want to keep their disputes as calm and rational as possible. “When discussing a sensitive topic with your spouse, do it over dinner or after dinner,” he said. “Don’t do it on an empty stomach.”