The concept of being ‘hangry’ - angry because you’re hungry - comes up among ScienceAlert staff more than we’d like to admit. But there’s nothing wrong with being hangry - there’s a scientific reason why having low blood sugar can make some people aggressive.
According to a study published earlier this year, blood sugar levels directly correlated to how married couples were likely to treat each other. Working with 107 couples over three weeks, the researchers, led by psychologist Brad Bushman from the Ohio State University in the US, found that when individuals experienced lower than usual blood sugar levels, they became increasingly aggressive and downright mean towards their significant others.
This was measured through the use of a good old-fashioned voodoo doll - the volunteers were each given one, along with 51 pins, to represent their spouse. Each person’s aggressive impulses were then measured based on how many pins they stuck into their spouse-dolls every night throughout the experiment.
Aggression, on the other hand, was measured by volunteers blasting their spouse with a loud and unpleasant noise in the headphones they had to wear. Think nails on a chalkboard, or a dentist’s drill.
Turns out that the volunteers who experienced the lowest blood sugar levels stuck more pins into their voodoo dolls, and inflicted louder and longer blasts of noise on their spouses than those who had plenty of glucose in their system.
"People are often the most aggressive against the people to whom they are closest - intimate partners,” the researchers concluded. "Intimate partner violence might be partly a result of poor self-control. Self-control of aggressive impulses requires energy, and much of this energy is provided by glucose derived from the food we eat."
As Susannah Locke explains at Vox, glucose is the only molecule that our brains will accept as fuel. This means, quite simply, that when we’re not producing enough glucose, our brains won’t function properly. It also means that we lack the energy we need to maintain self-control, which is why we’re more likely to lash out in an uncharacteristic manner when we haven’t eaten in a while.
But not all hanger is born equal. I’ll be the first to admit that I’ve had some legendary hangry moments, whereas my significant other has probably never experienced one in his life. Research has shown that low glucose levels affect people differently.
"One key long-term study from back in 1984 demonstrated that these variations could predict future violent episodes in 84 percent of criminals. (This kind of research can get tricky, though, because glucose regulation can be influenced by many other factors, as well.)”, says Locke.
And another research project carried out in 2011 by physiologist C. Nathan DeWall from the University of Kentucky in the US and colleagues looked at the link between aggressive and violent behaviours and low glucose levels and poor glucose metabolism across four different studies.
The results were laid out in the aptly named journal, Aggressive Behaviour:
"Study 1 found that participants who consumed a glucose beverage behaved less aggressively than did participants who consumed a placebo beverage.
Study 2 found an indirect relationship between diabetes (a disorder marked by low glucose levels and poor glucose metabolism) and aggressiveness through low self-control.
Study 3 found that [American] states with high diabetes rates also had high violent crime rates.
Study 4 found that countries with high rates of glucose-6-phosphate dehydrogenase deficiency (a metabolic disorder related to low glucose levels) also had higher killings rates, both war related and non-war related.
All four studies suggest that a spoonful of sugar helps aggressive and violent behaviours go down."
What we can take from this research in particular is that something sugary can stem hangry behaviour when things get desperate. At Vox, Locke talks about another study that separated people into two groups - those who drank lemonade and those who were given a placebo - and asked them to blast other participants with loud noises when they felt like it. Surprise, surprise, the lemonade-drinking participants were more mellow than their hangry placeeboed counterparts. "A similar investigation showed that sugared-up subjects were less likely to appear frustrated while playing an impossibly difficult computer game," says Locke.
Someone pass me a biscuit, for all our sakes.