Functional connectivity dynamics slow with descent from wakefulness to sleep

PLoS One. 2019 Dec 2;14(12):e0224669. doi: 10.1371/journal.pone.0224669. eCollection 2019.


The transition from wakefulness to sleep is accompanied by widespread changes in brain functioning. Here we investigate the implications of this transition for interregional functional connectivity and their dynamic changes over time. Simultaneous EEG-fMRI was used to measure brain functional activity of 21 healthy participants as they transitioned from wakefulness into sleep. fMRI volumes were independent component analysis (ICA)-decomposed, yielding 42 neurophysiological sources. Static functional connectivity (FC) was estimated from independent component time courses. A sliding window method and k-means clustering (k = 7, L2-norm) were used to estimate dynamic FC. Static FC in Wake and Stage-2 Sleep (NREM2) were largely similar. By contrast, FC dynamics across wake and sleep differed, with transitions between FC states occurring more frequently during wakefulness than during NREM2. Evidence of slower FC dynamics during sleep is discussed in relation to sleep-related reductions in effective connectivity and synaptic strength.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Mapping
  • Electroencephalography
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Nerve Net / diagnostic imaging
  • Nerve Net / physiology*
  • Sleep / physiology*
  • Wakefulness / physiology*
  • Young Adult

Grants and funding

This research was supported in part by the Canada Excellence Research Chairs (CERC) Program (215063). This research was also supported by an NSERC Discovery Grant awarded to JBM. Research was conducted with the assistance of the Centre for Metabolic Mapping, Robarts Research Institute, Western University. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.