Mastication while rested does not improve sustained attention in healthy participants conducting short-duration cognitive tasks

Sustained attention is important for optimal neurobehavioral performance, but many biological and environmental factors (e.g., circadian rhythm, distraction, etc.) may cause sustained attention deficits. It has been suggested that mastication (chewing) may ameliorate such deficits. We used a randomized, within-subjects, cross-over design to investigate the effect of mastication (gum chewing) on levels of sustained attention. To initially provide data that was ecologically valid for the average person, participants were not sleep deprived or otherwise challenged. Fifty-eight healthy adults (aged 18-45 years; 38 females) completed a 5 h in-laboratory daytime study during which time they completed two, 40 min test bouts. Participants completed the Psychomotor Vigilance Test (PVT), the Sustained Attention to Response Task (SART), the Karolinska Sleepiness Scale (KSS) and the Positive and Negative Affect Schedule (PANAS). During one of the two test bouts, participants were instructed to chew a piece of gum at a steady, comfortable rate. The statistical analyses were conducted blind. The primary outcome variable used for analyses was PVT lapses using the transformation square root of lapses plus square root of lapses plus 1 in addition to PVT mean reciprocal response time. Secondary outcome variables were PVT time-on-task slope and SART error score. Using rested participants and moderately fatiguing tasks, we were unable to detect any significant improvement in PVT or SART performance, or in KSS or PANAS ratings. A follow-up study under conditions of sleep deprivation and/or with longer task duration may provide further insight into the countermeasure potential of mastication.