Recovery sleep attenuates impairments in working memory following total sleep deprivation

Short-term recovery sleep attenuates the impairment of response inhibition after total sleep deprivation: Evidence from an event-related potentials study

OBJECTIVES

Sleep deprivation is increasingly a problem in modern society. Therefore, understanding the restorative effects of short naps on cognitive function after sleep deprivation has considerable relevance. This study investigated changes in response inhibition function after 30 h of total sleep deprivation (TSD) and the impact of 1 h of recovery sleep (RS) on the recovery of this function.

METHODS

Twenty-seven healthy male participants performed a visual Go/No-Go task while event-related potentials (ERP) were recorded. Response inhibition was assessed at three time points: at baseline (0 h of TSD), after 30 h of TSD, and after 1 h of RS.

RESULTS

The results from the behavioral indicators revealed a significant increase in reaction times to the Go stimuli (p = 0.013), a decrease in accuracy (p < 0.001), and a substantial rise in the error rate for the No-Go stimuli (p = 0.001) after 30 h of TSD compared with baseline. After 30 h of TSD, there was no significant improvement in task performance after 1 h of RS. ERP analysis showed a significant prolongation of the latencies of N2 (p = 0.012) and P3 (p = 0.010), a significant increase in P3 amplitude (p = 0.048), and no significant change in N2 amplitude after TSD compared with that at baseline. After 1 h of RS, N2 amplitude significantly increased (p = 0.010) and P3 latency remained prolonged (p = 0.008).

CONCLUSIONS

After thirty hours of sleep deprivation, the brain maintains task performance primarily through compensatory mechanisms. 1 h of RS partially ameliorates the impaired response inhibition caused by thirty hours of sleep deprivation, restoring this function closer to baseline levels.

Development and preliminary validation of a standardized measure of neuropsychological assessment readiness

Neuropsychological evaluations are typically conducted under specific preconditions as it has been long established that many factors unrelated to an individual's true neurocognitive functioning can influence their cognitive test performance. Assessment readiness refers to the extent to which a client is in a state appropriate for undergoing a neuropsychological evaluation (e.g., well rested, sober) as well as any atypical characteristics that require specific accommodations from the administering clinician (e.g., mobility limitations, colorblindness). The purpose of this study was to propose and investigate the preliminary validation of a screening measure of assessment readiness in order to introduce a systematic method for assessing this novel construct. Younger and older adults (N = 93) were administered the Barnett-Coldiron Assessment Readiness Inventory (BCARI) prior to completing a short battery of neuropsychological tests. Additionally, subject matter experts (SMEs) were asked to rate the content validity of this inventory. The BCARI showed preliminary evidence of discriminant validity when compared to other neuropsychological tests and produced the expected minimal variance in assessment readiness scores among healthy, assessment-ready participant samples and across multiple demographic variables. SMEs were largely in support of the BCARI as a valid scale for measuring assessment readiness and positively rated its application in both clinical and research settings. The BCARI shows potential as a useful tool in evaluating the profile validity of clients prior to neuropsychological testing and for reporting a standardized measure of assessment readiness within the profile validity of evaluation reports and research articles.

Sleep deprivation alters utilization of negative feedback in risky decision-making

Background

Sleep loss has sometimes catastrophic effects on risky decision-making. However, it is unknown to what extent such deficits are exacerbated with increasing duration of sleep deprivation (SD) and whether sustained vigilant attention mediates this sleep deprivation-induced deficit.

Methods

The present study aimed to investigate the effect of 36 hours of SD on 37 male college students' arousal, emotion, vigilant attention, and risky decision-making, using the Psychomotor Vigilance Test, the Game of Dice Task, and scales assessing fatigue, sleep, and emotions.

Results

Compared to baseline, SD significantly increased sleepiness, fatigue, and negative emotions, decreased positive emotions and vigilant attention, and led to a shift toward risky decision-making, and these effects often appeared 15 or 20 hours after SD. Interestingly, participants' ability to employ positive feedback was maintained, whereas their performance to utilize negative feedback was impaired even after 8 hours of sleep deprivation. Meanwhile, vigilant attention acted as a mediator between SD and risky decision-making (z = -1.97, 95% [-6.00, -0.30]).

Discussion

These results suggest that sleep-deprived individuals are unable to use negative feedback to optimize their judgments, which may account for their poor decision-making under risk.

Preoperative recovery sleep ameliorates postoperative cognitive dysfunction aggravated by sleep fragmentation in aged mice by enhancing EEG delta-wave activity and LFP theta oscillation in hippocampal CA1

Sleep fragmentation (SF) is a common sleep problem experienced during the perioperative period by older adults, and is associated with postoperative cognitive dysfunction (POCD). Increasing evidence indicates that delta-wave activity during non-rapid eye movement (NREM) sleep is involved in sleep-dependent memory consolidation and that hippocampal theta oscillations are related to spatial exploratory memory. Recovery sleep (RS), a self-regulated state of sleep homeostasis, enhances delta-wave power and memory performance in sleep-deprived older mice. However, it remains unclear whether RS therapy has a positive effect on cognitive changes following SF in older mouse models. Therefore, this study aimed to explore whether preoperative RS can alleviate cognitive deficits in aged mice with SF. A model of preoperative 24-h SF combined with exploratory laparotomy-induced POCD was established in 18-month-old mice. Aged mice were treated with preoperative 6-h RS following SF and postoperative 6-h RS following surgery, respectively. The changes in hippocampus-dependent cognitive function were investigated using behavioral tests, electroencephalography (EEG), local field potential (LFP), magnetic resonance imaging, and neuromorphology. Mice that underwent 24-h SF combined with surgery exhibited severe spatial memory impairment; impaired cognitive performance could be alleviated by preoperative RS treatment. In addition, preoperative RS increased NREM sleep; enhanced EEG delta-wave activity and LFP theta oscillation in the hippocampal CA1; and improved hippocampal perfusion, microstructural integrity, and neuronal damage. Taken together, these results provide evidence that preoperative RS may ameliorate the severity of POCD aggravated by SF by enhancing delta slow-wave activity and hippocampal theta oscillation, and by ameliorating the reduction in regional cerebral blood flow and white matter microstructure integrity in the hippocampus.