In an article recently out in Conscious and Cognition, Óscar Goncalves along with colleagues from Tilburg University and University of Madeira, showed that our typical daily oscillation between focused and wandering consciousness is associated in the attenuation of some of the neurophysiological markers of consciousness access.
Namely, prior to entering in a state of consciousness wandering the researchers found an attenuation of P3 wave and increase in the power of low frequency bands (theta, alpha) and decrease in higher frequency bands (beta, gamma).
This suggests consciousness access may not an all-or-nothing phenomenon, but that some consciousness access markers are present in different degrees in distinct consciousness states.
M.R. Dias da Silva, Ó.F Gonçalves, D. Branco, M. Postma, Revisiting consciousness: Distinguishing between states of conscious focused attention and mind wandering with EEG, Consciousness and Cognition, Volume 101, 2022, 103332, ISSN 1053-8100, https://doi.org/10.1016/j.concog.2022.103332.