How the time-of-day affects the EEG signatures of vigilance fluctuation

ABSTRACTPrevious research suggested the homeostatic effect on the top-down control system as a major factor for daytime vigilance decrement, yet how it alters the cognitive processes of vigilance remains unclear. Using EEG, the current study measured the vigilance of 28 participants under three states: the morning, the midafternoon after napping and no-nap. The drift-diffusion model was applied to decompose vigilant reaction time into decision and non-decision components. From morning to midafternoon, vigilance declined during sustained wakefulness, but remained stable after midday napping. Increased sleep pressure negatively affected decision time and drift rate, but did not significantly alter the non-decision process. Frontocentral N2 amplitude decreased from morning to no-nap afternoon, associated with slowing decision time. In contrast, parietal P3 had no diurnal alterations during sustained wakefulness, but enhanced after napping. Pre-stimulus parietooccipital alpha power enhanced under high sleep pressure relative to low, accompanied by more lapses in no-nap vs. post-napping conditions. The homeostasis effect is a major contributor to daily vigilance fluctuation, specifically targeting top-down control processes during the pre-stimulus and decision-making stages. Under the influence of sleep homeostasis, the speed of decision-making declines with degradation in target monitoring from morning to afternoon, leading to post-noon vigilance decrement.KEYWORDS: Time-of-day effecthomeostatic sleep pressurevigilancepre-stimulus alphadrift diffusion model AcknowledgmentsThis work was supported by The MOE (Ministry of Education in China) Project of Humanities and Social Sciences (No. 21YJC190011), Guangdong Basic and Applied Basic Research Foundation (No. 2023A1515011873) and Natural Science Foundation of SZU (No. 827-000259).Author contributionsTian Xie: Data curation, formal analysis, visualization, writing – revising original draft; Mingzhu Li: Formal analysis, methodology; Chao Hao: Data curation, formal analysis, methodology; Yudi Peng: Data curation, formal analysis; Wei Luo; funding acquisition, resources; review and editing original draft; Ning Ma: Conceptualization, funding acquisition, resources; writing – review and editing, supervision, validation.Disclosure statementNo potential conflict of interest was reported by the authors.Data accessibility statementThe data that support the findings of this study are available on request from the corresponding author.Additional informationFundingThe work was supported by the Basic and Applied Basic Research Foundation of Guangdong Province [2023A1515011873]; The MOE (Ministry of Education in China) Project of Humanities and Social Sciences [21YJC190011]; Natural Science Foundation of SZU [827-000259].