Effect of a Whole-Food Plant-Based Diet on Postprandial Sleepiness: A Pilot Study

Background: Postprandial sleepiness refers to the state of excessive drowsiness that occurs after consuming a meal. This transient phenomenon is experienced by many individuals, often leading to decreased productivity and impaired cognitive performance. This study examined the effect of a whole-food plant-based (WFPB) diet on postprandial sleepiness. Methods: Ten participants who had postprandial sleepiness who were on a typical American diet transitioned to a WFPB dietary pattern for 21 days. Postprandial sleepiness was assessed using the Epworth Sleepiness Scale (ESS) questionnaire, focusing on Q7 “sitting quietly after lunch without alcohol” as well as Q5 “lying down to rest in the afternoon when circumstances permit.” Results: The participants had a mean age of 44 +/− 15 years, with 30% being male. There was a statistically significant reduction in sleepiness measured by ESS Q7 (median change = −1, P =.012) and ESS Q5 (median change = −1.5, P =.008). Moreover, there was a statistically significant decrease in overall ESS scores (median change = −8.0, P =.006), and weight (median change = −2.9 kg, P =.006). Conclusion: Participants demonstrated significant improvement in postprandial sleepiness-related situations. Our findings showed that the WFPB diet may have potential benefits for reducing postprandial and overall daytime sleepiness.