High glycaemic index (GI) breakfasts resulting in sharp rises in blood glucose may adversely affect memory and attention, particularly in the late postprandial phase (i.e., 120-180 minutes after breakfast). Previous research indicates that breakfast GI influences cognition in young adults, but many studies were too short to capture late postprandial effects. However, young adults may be particularly responsive to these adverse effects on cognition since they are prone to experience circadian misalignment in the morning due to the fact that their midpoint of sleep (i.e., chronotype) is biologically most delayed. Our recent research suggests that persons with later chronotypes do not display the known circadian decline in glucose tolerance as evidenced by equally high glycaemic responses to the identical high GI meal consumed in the morning or the evening. Hence, consuming an early breakfast "against the inner clock" may negatively affect glycaemic response particularly among persons with a later chronotype. Whether this vulnerability for persons with a later chronotype may extend to effects on cognition has not been examined. Thus, the main objective of this controlled nutrition trial is to analyze the effects of a high versus a low GI beverage as a breakfast on subsequent memory and attention until 180 minutes after breakfast among young healthy university students. This will be examined in two samples, i.e. students with an earlier and with a later chronotype. Accordingly, our study will allow us to explore the relevance of chronotype for (i) the postprandial course of glucose levels and (ii) the course of memory and attention per se in the postprandial phase. In preparation for the present study, at Paderborn University 356 students (aged 18-25) were enrolled between October 2024 and January 2025 in the GlyCoBrain Observational study (ID: NCT06679088) and were screened for their chronotypes. From these, persons with the earliest and latest chronotype will be invited to participate in the present cross-over designed study. It is planned that overall 88 persons will complete both intervention days consuming either a high GI or a low GI breakfast at 9:00 a.m. and undergoing repeated assessment of cognitive performance during the subsequent 180 minutes.
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Difference in immediate verbal memory
Timeframe: 150-180 minutes