Gum chewing modulates heart rate variability under noise stress

Objective: Gum chewing may relieve stress, although this hypothesis has not been proven. Heart-rate variability (HRV) is commonly used to measure stress levels. However, it is not known if gum chewing modulates HRV under acute stress. The aim of this study was to investigate the effects of gum chewing on HRV under acute stress. Materials and methods: A crossover study involving 47 non-smoking healthy subjects, aged 22-27 years, was carried out. The subjects received a stress procedure with gum chewing (GS group) and without gum chewing (S group). Additionally, the other 20 subjects were allocated to the gum chewing without stress group (G group). The GS and S groups were exposed to noise for 5 min (75 dBA) as stress. Before and after stress exposure/gum chewing, participants completed the state portion of the State-Trait Anxiety Inventory (STAI-s) and a single Stress Visual Analogue Scale (VAS) measurement. HRV measurement was performed before and during stress/gum chewing for 5 min. Results: After the stress procedure, VAS score significantly increased in the GS and S groups. During the stress procedure, the GS group showed a significantly lower level of high frequency (HF) and higher levels of low frequency (LF) and LF/HF than the S group. However, there were no significant differences in the scores of the state portion of the State-Trait Anxiety Inventory (STAI-s) and VAS between the two stress groups. Conclusions: These findings suggest that gum chewing modulates HRV, but may not relieve acute stress caused by noise.