title: Labile sleep promotes awareness of abstract knowledge in a serial reaction time task.
abstract: Sleep has been identified as a critical brain state enhancing the probability of gaining insight into covert task regularities. Both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep have been implicated with oﬄine re-activation and reorganization of memories supporting explicit knowledge generation. According to two-stage models of sleep function, oﬄine processing of information during sleep is sequential requiring multiple cycles of NREM and REM sleep stages. However, the role of overnight dynamic sleep macrostructure for insightfulness has not been studied so far. In the present study, we test the hypothesis that the frequency of interactions between NREM and REM sleep stages might be critical for awareness after sleep. For that aim, the rate of sleep stage transitions was evaluated in 53 participants who learned implicitly a serial reaction time task (SRTT) in which a determined sequence was inserted. The amount of explicit knowledge about the sequence was established by verbal recall after a night of sleep following SRTT learning. Polysomnography was recorded in this night and in a control night before and was analyzed to compare the rate of sleep-stage transitions between participants who did or did not gain awareness of task regularity after sleep. Indeed, individual ability of explicit knowledge generation was strongly associated with increased rate of transitions between NREM and REM sleep stages and between light sleep stages and slow wave sleep. However, the rate of NREM-REM transitions specifically predicted the amount of explicit knowledge after sleep in a trait-dependent way. These results demonstrate that enhanced lability of sleep goes along with individual ability of knowledge awareness. Observations suggest that facilitated dynamic interactions between sleep stages, particularly between NREM and REM sleep stages play a role for oﬄine processing which promotes rule extraction and awareness.
authors.affiliation: Cognitive Psychophysiology, Institute of Neurobiology, Bulgarian Academy of Sciences Sofia, Bulgaria.
authors.forename: Roumen
authors.initials: R
authors.lastname: Kirov
authors.affiliation: Cognitive Psychophysiology, Institute of Neurobiology, Bulgarian Academy of Sciences Sofia, Bulgaria ; Department of Neurology, University of Lübeck Lübeck, Germany.
authors.forename: Vasil
authors.initials: V
authors.lastname: Kolev
authors.affiliation: Department of Neurology, University of Lübeck Lübeck, Germany ; Institute of Psychology II, University of Lübeck Lübeck, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Verleger
authors.affiliation: Cognitive Psychophysiology, Institute of Neurobiology, Bulgarian Academy of Sciences Sofia, Bulgaria ; Department of Neurology, University of Lübeck Lübeck, Germany.
authors.forename: Juliana
authors.initials: J
authors.lastname: Yordanova
keywords: NREM–REM–NREM transitions; explicit knowledge; insight; labile sleep; serial reaction time task; sleep stage transitions