WASHINGTON, April 14 (Xinhua) -- Lower levels of blood sugar may make married people angrier and more aggressive against their spouses, according to a new U.S. study released Monday.
The study revealed how hunger caused by low levels of blood glucose may play a role in marital arguments, confrontations, and possibly even some domestic violence, said Brad Bushman, lead author and professor of communication and psychology at the Ohio State University.
The aggressive behavior has a slang term: "hangry" (hungry + angry). "People can relate to this idea that when they get hungry, they get cranky," Bushman said.
The study, published in the U.S. Proceedings of the National Academy of Sciences, involved 107 married couples and measured anger in a unique way validated in previous studies.
All participants were given a voodoo doll that they were told represented their spouse, along with 51 pins. At the end of each day, for 21 consecutive days, the participants inserted 0 to 51 pins in the doll, depending on how angry they were with their spouse. They did this alone, without their spouses being present, and recorded the number of pins they stuck in the doll.
Each person also used a blood glucose meter to measure glucose levels before breakfast and every evening before bed for the 21 days. The researchers found that the lower the participants' evening blood glucose levels, the more pins they stuck in the doll.
"When they had lower blood glucose, they felt angrier and took it out on the dolls representing their spouse," Bushman said. " Even those who reported they had good relationships with their spouses were more likely to express anger if their blood glucose levels were lower."
After the 21 days, the couples came into the laboratory to take part in an experimental task.
They were told they would compete with their spouse, although the opponent was actually a computer, to see who could press a button faster when a target square turned red on the computer and the winner on each trial could blast his or her spouse with loud noise through headphones.
Each time they "won", the participants decided how loud a noise they would deliver to their spouse and how long it would last. Their spouses were in separate rooms during the experiment, so participants did not know they were not really delivering the noise blast.
"Within the ethical limits of the lab, we gave these participants a weapon that they could use to blast their spouse with unpleasant noise," Bushman said.
Results showed that people with lower average levels of evening glucose sent louder and longer noise to their spouse.
Further analysis found that those who stuck more pins in the voodoo doll representing their spouse were more likely to deliver louder and longer noise blasts as well.
"We found a clear link between aggressive impulses as seen with the dolls and actual aggressive behavior," Bushman said.
As to why low blood sugar can make people more prone to anger and aggression, Bushman said the self-control needed to deal with anger and aggressive impulses takes energy, and that energy is provided in part by glucose, which is fuel for the brain.
"Even though the brain is only 2 percent of our body weight, it consumes about 20 percent of our calories. It is a very demanding organ when it comes to energy," he said.
"It's simple advice but it works: Before you have a difficult conversation with your spouse, make sure you're not hungry," he added.