Do people really get "hangry"? A 21-day research study has found that people do, in fact, get angry and irritable as they get hungrier.

The term "hangry" refers to the feeling of getting angry due to hunger, and it has become a pretty common term that many people use. However, the phenomenon hasn't been "widely explored outside of laboratory experiments," Anglia Ruskin University (ARU) noted in a news release.

"(B)oth conceptual and historical accounts suggest that hunger often leads to negative emotions, including anger and irritability," the researchers wrote in their paper, published Wednesday in the journal PLOS ONE. "Yet, despite this, surprisingly little research has focused on the experience, manifestation, and consequences of being hangry, particularly in everyday settings."

To shed light on the matter, the researchers conducted a study to determine "the extent" to which people's hunger is associated with anger fluctuations. 64 participants in central Europe recorded their feelings and levels of hunger in their everyday environments. They did this five times a day through a questionnaire via an app on their smartphones.

Three of the times are fixed at breakfast, lunch and dinner time as these are said to be the times of the day when "hunger is likely heightened," while the other two were random.

Among the questions participants had to answer was "How hungry are you at the moment?" and they could rate it from zero (not hungry at all) to 100 (very hungry). Other questions such as "How irritable do you feel at the moment?" and "How angry are you at the moment?" also had a similar format. The study went on for three weeks.

"Results indicated that greater levels of self-reported hunger were associated with greater feelings of anger and irritability, and with lower pleasure," the researchers wrote. "These findings remained significant after accounting for participant sex, age, body mass index, dietary behaviors, and trait anger."

According to the researchers, the results support the idea of being "hangry." It also adds to the body of research showing that hunger levels or blood glucose levels can impact people's anger and irritability. The "novelty" of the study is that they were able to show it outside the laboratory and instead in people's normal lives, the researchers noted.

The lead author of the study, Viren Swami of ARU, noted that theirs is the "first study to examine being 'hangry' outside of a lab."

"Although our study doesn't present ways to mitigate negative hunger-induced emotions, research suggests that being able to label an emotion can help people to regulate it, such as by recognizing that we feel angry simply because we are hungry," Swami said in the university news release. "Therefore, greater awareness of being 'hangry' could reduce the likelihood that hunger results in negative emotions and behaviors in individuals."