Article

Assessing sleep consciousness within subjects using a serial awakening paradigm

Department of Psychiatry, University of Wisconsin Madison, WI, USA.
Frontiers in Psychology (Impact Factor: 2.8). 08/2013; 4:542. DOI: 10.3389/fpsyg.2013.00542
Source: PubMed

ABSTRACT

Dreaming-a particular form of consciousness that occurs during sleep-undergoes major changes in the course of the night. We aimed to outline state-dependent features of consciousness using a paradigm with multiple serial awakenings/questionings that allowed for within as well as between subject comparisons. Seven healthy participants who spent 44 experimental study nights in the laboratory were awakened by a computerized sound at 15-30 min intervals, regardless of sleep stage, and questioned for the presence or absence of sleep consciousness. Recall without content ("I was experiencing something but do not remember what") was considered separately. Subjects had to indicate the content of the most recent conscious experience prior to the alarm sound and to estimate its duration and richness. We also assessed the degree of thinking and perceiving, self- and environment-relatedness and reflective consciousness of the experiences. Of the 778 questionings, 5% were performed during wakefulness, 2% in stage N1, 42% in N2, 33% in N3, and 17% in rapid eye movement (REM) sleep. Recall with content was reported in 34% of non-REM and in 77% of REM sleep awakenings. Sleep fragmentation inherent to the study design appeared to only minimally affect the recall of conscious experiences. Each stage displayed a unique combination of characteristic features of sleep consciousness. In conclusion, our serial awakening paradigm allowed us to collect a large and representative sample of conscious experiences across states of being. It represents a time-efficient method for the study of sleep consciousness that may prove particularly advantageous when combined with techniques such as functional MRI and high-density EEG.

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Available from: Joshua J LaRocque, Apr 14, 2014
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    • "Some experiments with transcranial magnetic stimulation do demonstrated, in human subjects, reduced number of the cortical areas activated in response to such direct stimulation of the cortex during sleep (Massimini et al., 2010). However, earlier experiments in animals (Berlucchi et al., 1967) demonstrated strong reduction of callosal connectivity during REM sleep—the period when information integration theory predicted increase of transcortical integration of information because of dreaming recognized by this theory as indication of consciousness emerging during sleep (Siclari et al., 2013). In parallel with the attempts to stay within the traditional paradigm, more and more scientists associated the highest brain functions not with the cortical activity but with the " supracortical " levels of information processing, for example the basal ganglia (e.g.,Crick and Koch, 2005;Stocco et al., 2010;Koubeissi et al., 2014;Stiefel et al., 2014). "
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    • "From an evolutionary point of view, it is extremely unlikely that phenomenal consciousness evolved aer (or at the same time as the) acquisition of verbal or motor reports. We humans have conscious experience all the time from the moment we get up in the morning until we fall asleep at night as well as during vivid dreaming in sleep (Siclari, Larocque, Postle, & Tononi, 2013 ). However, we rarely report what we experience to other people, except during psychophysical experiments and limited other occasions. "

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