The Effect of Thorough Chewing on Postprandial Sleepiness

Apart from other factors, postprandial sleepiness depends on types and amount of food ingested. Eating slowly has been shown to reduce meal size and total energy intake. It was therefore hypothesized that the level of postprandial sleepiness could be reduced by thorough chewing. OBJECTIVES: To compare the level of postprandial sleepiness between habitually fast and thorough chewing. METHODS: Fifteen dental students who reported to be fast eaters and usually felt asleep after lunch were asked to eat the same test lunch in two different sessions, one with habitual and the other with thorough chewing (more than 30 chews/spoonful with spoon and fork put down after each chew). Surface EMGs of the masseter and suprahyoid muscles were used to monitor the number of chews and the moment of swallowing. The VAS of postprandial sleepiness and the number of yawns were compared, along with the amount of overall food intake. RESULTS: The overall sleepiness VAS was significantly lower in thorough chewing (4.0±2.4) compared to that in habitual fast chewing (6.0±2.2) (p=0.007), whereas the amount of total food intake were not significantly different. CONCLUSIONS: Thorough chewing can reduce postprandial sleepiness. The mechanism is unknown but probably not mediated by the amount of food ingested. (Supported by Student Research Grant, Faculty of Dentistry, KKU)