A new study finds that lowered blood glucose levels exacerbate marital strife.

Marriage. What’s love got to do with it? Well, a lot, as it turns out—but you may also want to ask, “What’s glucose got to do with it?” A new study of married couples finds that lower levels of blood glucose may make married people both angrier at their spouses and more aggressive toward them.

The study, which was published in the Proceedings of the National Academy of Sciences, looked at 107 married couples married 12 or more years.

At the onset of the study, the couples completed a survey that measured relationship satisfaction.

The research, which was conducted in people’s homes, required that each spouse measure glucose levels with a blood glucose monitor. Readings were taken before breakfast and every evening before bed, for 21 days.

Related News: The Key to a Happy Marriage May Lie in Your Genes »

Each participant in the study was given a voodoo doll, which they were told represented their spouse, along with 51 pins. At the end of each day, participants inserted between 0 and 51 pins in the doll, depending on how angry they were with their mate.

The researchers found that participants with low blood glucose stuck more pins into the dolls. Study results suggest that low glucose levels may decrease a person’s ability to control emotions such as aggression. “We found that being ‘hangry’ [a combination of ‘hungry’ and ‘angry’] can affect our behavior in a bad way, even in our most intimate relationships. Even those who reported they had good relationships with their spouses were more likely to express anger if their blood glucose levels were lower. We found a clear link between aggressive impulses as seen with the dolls and actual aggressive behavior,” said lead author Brad J. Bushman, Ph.D., professor of communication and psychology at The Ohio State University.

Following the 21-day study, participants played a game in which they were told they would play against their spouse. The winner of each of the 25 trials could control the volume and duration of a loud, harsh sound to be delivered to the loser. (The opponent was a computer; spouses did hear noise in half the trials.)

Participants with lower average levels of evening glucose delivered louder and more prolonged noises to their spouse, even after controlling for relationship satisfaction and differences between men and women, according to the study.

Learn How Extra Pounds Can Destroy Your Love Life »

Bushman told Healthline, “Our brain is less than 2 percent of our body weight, but it consumes about 20 percent of our calories. It demands a lot of energy, which it gets from the foods we eat.”

He added, “Glucose is the food that the brain requires in order to exercise self-control. By far, the emotion that is the most difficult for people to control is anger. The area behind the forehead, the prefrontal cortex, is in charge of executing functions, such as controlling emotions. It demands a lot of energy to control your emotions.”

According to Bushman, this energy can be depleted over time, leading to an erosion of self-control. Aggressive impulses, sometimes directed at a spouse, may emerge as failures of self-control.

Julia Samton, M.D., board certified in psychiatry and neurology, and director of Manhattan Neuropsychiatric, in New York, told Healthline, “When our blood sugar is low our body treats it as a crisis. Our adrenal glands get stimulated, and they send out a number of hormones and communicate to our entire body and brain that we are in crisis. We get more irritable, more hostile, and anxious. Hormones are very powerful chemicals.”

Get the Facts: 7 Foods That Can Enhance Your Sex Life »

Samton said that fatigue and drinking alcohol may also be to blame. “When we are tired, we have lower frustration tolerance and it can be more difficult to take things in stride. Sometimes if we’ve had too much to drink, we might be less inhibited and say things that we may be feeling that we might not necessarily articulate.”

Commenting on Bushman’s findings, Allison Rumsey, RD, CDN, CNSC, CSCS, a registered dietitian and spokesperson for the New York State Dietetic Association, told Healthline that when blood sugar is low, it can cause an imbalance of several hormones in our body that regulate both mood and appetite. “Anger and frustration are common responses to low blood sugar. Blood sugar has to drop pretty low for this to happen, and generally takes several hours of not eating.”

Emphasizing that some people are more prone to having low blood sugar than others and that these people are likely to have more severe symptoms, Rumsey said that anger, as a result of hunger, is also partly based on personality.

About coining the word “hangry,” Bushman said, “Hungry people tend to be angry. Blood glucose levels can be brought up most quickly by eating carbohydrates or sugary foods.” Emphasizing that he doesn’t advocate eating a lot of candy bars even though they raise glucose fast, Bushman said, “A better way to raise glucose is by eating protein, such as protein bars and protein drinks, and eating vegetables. These foods will take longer to raise glucose, but glucose will remain elevated longer.”

Rumsey advised that in order to keep blood sugar stable and ward off feeling “hangry,” a combination of protein and carbs should be consumed every three to four hours. “This could be something as simple as carrots, hummus, peanut butter, banana, cheese, or whole-grain crackers,” Rumsey advised.

“It’s simple advice, but it works,” Bushman said. “Before you have a difficult conversation with your spouse, make sure you’re not hungry.”