Network characteristics of brain-brain interactions of the inter-channel sub-networks.

<p>Pronounced sleep-stage stratification pattern is observed in both (a) number of links and (b) group averaged links strength. Notably, there is a significant difference between LS and DS, as well as between W and REM. This is in contrast to traditional sleep-stage classification of physiologic dynamics of individual systems, where DS and LS are considered similar states grouped as Non-REM state, that is separate from REM and W.