Evidence of sleep-facilitating effect on formation of novel semantic associations: An event-related potential (ERP) study

Reactive control in evaluating appropriately or inappropriately novel ideas: Evidence from electrophysiological measures

Novelty and appropriateness have been considered two necessary criteria to distinguish creative ideas, but little is known about what kind of reactive control people will make when they evaluate appropriately or inappropriately novel ideas. To study this issue, high-density technology was used to record electroencephalography (EEG) signals when participants were evaluating ideas in novel & appropriate, novel & inappropriate, ordinary & appropriate, and ordinary & inappropriate conditions. An analysis of event-related potentials (ERPs) revealed that greater conflict detection-related N2 and N400-like components over the anterior scalp appeared in novel conditions than in ordinary conditions, suggesting that people are able to rapidly monitor novel ideas. Afterward, the mean amplitudes of the LPC over the left anterior scalp were greater in novel & appropriate condition than ordinary & appropriate condition, but no difference was found between novel & appropriate and novel & inappropriate conditions, which likely displayed much more reactive control was recruited to handle novel ideas and no additional control was recruited when the novel ideas were inappropriate. In addition, the mean amplitudes of the LPC/LNC over the posterior scalp were greater in novel than ordinary conditions and were also greater in inappropriate than appropriate conditions, which likely reflected the processing difficulties of conceptual understanding. These findings revealed the early rise monitoring, conceptual understanding, and reactive control mechanism underlying the evaluation of novel ideas.

A daily diary study on maladaptive daydreaming, mind wandering, and sleep disturbances: Examining within-person and between-persons relations

Cross-sectional and experimental research have shown that task-unrelated thoughts (i.e., mind wandering) relate to sleep disturbances, but there is little research on whether this association generalizes to the day-level and other kinds of task-unrelated mentation. We employed a longitudinal daily diary design to examine the within-person and between-person associations between three self-report instruments measuring mind wandering, maladaptive daydreaming (a condition characterized by having elaborate fantasy daydreams so insistent that they interfere with daily functioning) and sleep disturbances. A final sample of 126 participants self-identified as experiencing maladaptive daydreaming completed up to 8 consecutive daily reports (in total 869 daily observations). The scales showed acceptable-to-excellent within-person reliability (i.e., systematic day-to-day change) and excellent between-person reliability. The proportion of between-person variance was 36% for sleep disturbances, 57% for mind wandering, and 75% for maladaptive daydreaming, respectively (the remaining being stochastic and systematic within-person variance). Contrary to our pre-registered hypothesis, maladaptive daydreaming did not significantly predict sleep disturbances the following night, B = -0.00 (SE = 0.04), p = .956. Exploratory analyses indicated that while nightly sleep disturbances predicted mind wandering the following day, B = 0.20 (SE = 0.04), p < .001, it did not significantly predict maladaptive daydreaming the following day, B = -0.04 (SE = 0.05), p = .452. Moreover, daily mind wandering did not significantly predict sleep disturbances the following night, B = 0.02 (SE = 0.05), p = .731. All variables correlated at the between-person level. We discuss the implications concerning the differences between maladaptive daydreaming and mind wandering and the possibility of targeting sleep for mind wandering interventions.

The impact of sleep deprivation on declarative memory

Sleep plays a crucial role in memory stabilization and integration, yet many people obtain insufficient sleep. This review assesses what is known about the level of sleep deprivation that leads to impairments during encoding, consolidation and retrieval of declarative memories, and what can be determined about the underlying neurophysiological processes. Neuroimaging studies that deprived sleep after learning have provided some of the most compelling evidence for sleep's role in the long-term reorganization of memories in the brain (systems consolidation). However, the behavioral consequences of losing sleep after learning-shown by increased forgetting-appear to recover over time and are unaffected by more common forms of partial sleep restriction across several nights. The capacity to encode new memories is the most vulnerable to sleep loss, since long-term deficits have been observed after total and partial sleep deprivation, while retrieval mechanisms are relatively unaffected. The negative impact of sleep loss on memory has been explored extensively after a night of total sleep deprivation, but further research is needed on the consequences of partial sleep loss over many days so that impairments may be generalized to more common forms of sleep loss.

Learning and sleep-dependent consolidation of spatial and procedural memories are unaltered in young men under a fixed short sleep schedule

OBJECTIVE

To investigate if a fixed short sleep schedule impairs one of the main functions of sleep, which is to consolidate newly learned memories.

METHODS

Sixteen young men participated in two experimental conditions, each of which lasted for 3 consecutive days and nights in our laboratory: a short sleep schedule (4.25-h sleep opportunity per night) versus a normal sleep schedule (8.5h per night). In the evening after two experimental nights, participants learned locations of 15 card pairs (spatial memory task) and a procedural finger tapping sequence task. Post-sleep retrieval of both memory tasks was tested the next morning.

RESULTS

The short sleep schedule, compared with the normal sleep schedule, considerably altered sleep characteristics, e.g. the proportion of time in slow-wave sleep increased across the three experimental nights. In contrast, neither learning in the evening of day 2, nor subsequent overnight memory consolidation (i.e. concerning the change in memory performance between pre-sleep learning on day 2 and post-sleep retrieval on day 3) differed between the normal and short sleep schedule conditions.

CONCLUSIONS

Our findings suggest that learning in the evening and subsequent sleep-dependent consolidation of procedural and spatial memories are unaltered in young men living under a fixed short sleep schedule. Future studies are warranted to validate our findings in other groups (e.g. adolescents and older subjects) and after more prolonged chronic sleep loss paradigms.