Scientists “don’t really know exactly how it works,” but the link between chewing and heightened attention is fairly strong, says Trulsson. There’s a caveat, though: “The effect will probably not last for more than 15 to 20 minutes”, although researchers aren’t sure why.
Another experiment – in young adults who were asked to perform four computerized tasks simultaneously – also found significantly better alertness (nearly 20% higher) in gum chewers. Interestingly, this was accompanied by reductions in self-reported anxiety, stress and salivary cortisol levels (a common biomarker of stress).
Lowering stress
Outside the lab, chewing is a good stress-reliever too. When a group of Turkish researchers studied 100 nursing students preparing for mid-term exams, they found that students who chewed gum for at least 30 minutes daily experienced lower levels of stress, anxiety and depression. This was regardless of whether they began chewing gum 15 days or two days before their exams.
For two separate groups of women undergoing elective gynaecological surgery in Korea, chewing on gum helped alleviate their pre-operative anxiety. It also had this effect on 73 Turkish children who were having an intravenous cannula inserted.
Chewing seems to be a natural reflex in stressful times, says Jianshe Chen, an oral processing researcher at Singapore’s Agency for Science, Technology and Research. “When some people are stressed, they start to chew unconsciously.” Teeth grinding or bruxism, which uses the same jaw muscles as chewing and affects roughly one in 10 adults, is commonly triggered by stress and anxiety.
But the scientific data here is more contentious. Chen, for instance, says the evidence linking chewing to a calmer state of mind is “scattered”. We’re “still short of systematic studies” that confidently point to a strong association, he says. Another study, led by the same Korean researcher above, for instance, found that gum-chewing did little to alleviate the anxiety pregnant women felt as they were wheeled into the operating theatre for an elective caesarean section. It also failed to dent the stress levels of those working on an insolvable word puzzle.
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