Total sleep deprivation (TSD) is common in modern society leading to deterioration of multiple aspects of cognition. Dynamic interaction effect of circadian rhythmicity and homeostatic sleep pressure on sustained attention have been intensively investigated, while how this effect was represented on performance and cerebral responses to working memory, another important element of many neurobehavioral tasks, was not well elucidated. Thirty-six healthy subjects with intermediate chronotype performed the Sternberg working-memory task (SWMT) while undergoing functional magnetic resonance imaging every 2 hr from 10:00 p.m. on the first day to 6:00 a.m. on the second day. Using data from three imaging sessions (10:00 p.m., 04:00 a.m., and 06:00 a.m.), we found that the slowest SWMT reaction time and weakest cerebral responses were not at the end of TSD (06:00 a.m.) but during the early morning (04:00 a.m.) hours of the TSD. In addition, during this worst period of TSD, reaction time for the SWMT were found to be negatively correlated with task-related activation in the angular gyrus and positively correlated with the degree of negative correlation between the control and default networks. Our results revealed a rebound of SWMT reaction time and cerebral responses after the mid-time point of regular biological sleep night and provided more evidence that different cognitive tasks are differentially affected by sleep loss and circadian rhythmicity. K E Y W O R D S dynamic changes, rebound response, sleep deprivation, working memory 1 | INTRODUCTION A single night of total sleep deprivation (TSD) produces a range of fundamental neurocognitive deficits and is associated with serious outcomes (Basner, Rao, Goel, & Dinges, 2013; Lim & Dinges, 2010). To understand the neural underpinnings of TSD-related deterioration within a specific cognitive domain, most imaging studies typically conduct two imaging sessions for each participant, one after TSD and the other after rested wakefulness (RW). The neurocognitive consequences of TSD were largely explained by comparing the differences in brain activity between these two sessions (Durmer & Dinges, 2005; Goel, Rao, Durmer, & Dinges, 2009). However, these types of observations describe modulated cerebral responses rather than the process through which the modulation occurs. A recent study exploring 13 repeated functional magnetic resonance imaging (fMRI) sessions during 42 hr of TSD found differential results for cortical and subcortical responses during a psychomotor vigilance task (PVT) and greatly expanded our understanding of how sustained attention deteriorates during TSD (Muto et al., 2016). Thus, to better understand how sleep deprivation impairs cognitive performance, increasing the numbers of sessions and investigating dynamic changes in behavioral and cerebral responses is critical. Yuanqiang Zhu, Yibin Xi, Jinbo Sun, Fan Guo authors contributed equally to this work.
