Wakefulness state modulates conscious access: Suppression of auditory detection in the transition to sleep

27 28 Neural basis of consciousness and its suppression are typically studied by manipulating stimuli 29 around the conscious access threshold, or – alternatively – by contrasting conscious and 30 unconscious states (i.e. awake/sleep). Here we show that behavioural and neural markers of 31 conscious access are dependent on wakefulness state, and thus a comprehensive description of the 32 neural basis of conscious access requires an integrated assessment of the state of consciousness. In 33 particular, we demonstrate that a distinctive steepness of a behavioural slope of conscious access is 34 severely compromised during the transition to sleep. Likewise, electrophysiological markers show a 35 delayed processing of target-mask interaction during drowsiness. Consequently, the resolution of 36 conscious access shifts from perceptual to executive stages of processing in the drowsy state of 37 consciousness. Once the goal is set – to report the awareness of a target – the brain is capable to 38 adapt to rapidly changing wakefulness states, revealing that the neural signatures of conscious 39 access and its suppression may not be hard-wired but flexible to maintain performance. 40 41 42