Recent research has found that the human sleep cycle is characterised by changes in spatiotemporal patterns of brain activity. Yet, we are still missing a mechanistic explanation of the local neuronal dynamics underlying these changes. We used whole-brain computational modelling to study the differences in global brain functional connectivity and synchrony of fMRI activity in healthy humans during wakefulness and slow-wave sleep. We applied a whole-brain model based on the normal form of a supercritical Hopf bifurcation and studied the dynamical changes when adapting the bifurcation parameter for all brain nodes to best match wakefulness and slow-wave sleep. Furthermore, we analysed differences in effective connectivity between the two states. In addition to significant changes in functional connectivity, synchrony and metastability, this analysis revealed a significant shift of the global dynamic working point of brain dynamics, from the edge of the transition between damped to sustained oscillations during wakefulness, to a stable focus during slow-wave sleep. Moreover, we identified a significant global decrease in effective interactions during slow-wave sleep. These results suggest a mechanism for the empirical functional changes observed during slow-wave sleep, namely a global shift of the brain’s dynamic working point leading to increased stability and decreased effective connectivity.

BMJ, RH, GH, APA and GD were funded by the European Research Council (ERC) Advanced Grant DYSTRUCTURE (n. 295129), European Union’s Horizon 2020 research and innovation programme under grant agreement No. 720270 (HBP SGA1) and No. 661583 (CONSBRAIN), by the Programa Estatal de Investigación Cientifica y Tecnica de Excelencia MINECO (PSI2013-42091, PSI2016-75688-P (AEI/FEDER, EU) and PCIN-2013-026), Juan de la Cierva fellowship (IJCI-2014-21066) and by the Catalan Agency for Management of University and Research Grants, AGAUR (2014SGR856). ET and HL were supported by the Bundesministerium für Bildung und Forschung (grantnumber 01 EV 0703) and the LOEWE Neuronale Koordination Forschungsschwerpunkt Frankfurt (NeFF). ET was further funded by a postdoctoral grant of the AXA foundation. MLK was supported by the ERC Consolidator Grant CAREGIVING (n. 615539).