The effect of total sleep deprivation on working memory: evidence from diffusion model.

STUDY OBJECTIVES: Working memory is crucial in human daily life and is vulnerable to sleep loss. The current study investigated the impact of sleep deprivation on working memory from the information processing perspective, to explore whether sleep deprivation affects the working memory via impairing information manipulation. METHODS: Thirty-seven healthy adults attended two counterbalanced protocols: a normal sleep night and a total sleep deprivation (TSD). The N-back and the psychomotor vigilance task (PVT) assessed working memory and sustained attention. Response time distribution and drift-diffusion model analyses were applied to explore cognitive process alterations. RESULTS: TSD increased the loading effect of accuracy, but not the loading effect of response time in the N-back task. TSD reduced the speed of information accumulation, increased the variability of the speed of accumulation, and elevated the decision threshold only in 1-back task. Moreover, the slow responses of PVT and N-back were severely impaired after TSD, mainly due to increased information accumulation variability. CONCLUSIONS: The present study provides a new perspective to investigate behavioral performance by using response time distribution and drift-diffusion models, revealing that sleep deprivation affected multicognitive processes underlying working memory, especially information accumulation processes.

To the Editor: Early school start times in middle and high schools have profound implications for children and teens.

This letter to the editor aims to prompt medical students, residents, and sleep medicine fellows to actively support the implementation of delayed school start times in middle and high schools, considering the significant impact it holds for children and adolescents. During puberty, research has demonstrated that circadian changes result in a sleep-phase delay among adolescents, leading them to sleep and wake up later compared to other age groups. This, coupled with early school start times, contributes to sleep deprivation within this patient population, increasing the likelihood of drowsy driving accidents, mental health problems, academic underperformance, and a predisposition to chronic illnesses like diabetes mellitus and hypertension. As medical students, residents, and fellows in the field of sleep, we must prioritize advocating for healthy sleep and addressing the issue of early school start times. By doing so, we can safeguard the future of medicine and society, ensuring the well-being and success of our middle and high school students. CITATION: Hernandez VK. To the editor: early school start times in middle and high schools have profound implications for children and teens. J Clin Sleep Med. 2024;20(4):671-672.

Impact of Sleep Deprivation on the Brain's Inflammatory Response Triggered by Lipopolysaccharide and Its Consequences on Spatial Learning and Memory and Long-Term Potentiation in Male Rats.

INTRODUCTION: Both sleep deprivation (SD) and inflammation can negatively affect cognitive function. This study aimed to investigate how SD impacts the brain's inflammatory response to lipopolysaccharide (LPS) and its subsequent effects on cognitive functions. METHODS: To this end, male rats were tested through a Morris water maze (MWM) to assess their spatial learning and memory. Also, in vivo field potential recordings (to evaluate synaptic plasticity) were done in the Saline, SD, LPS1 (1 mg/kg/7 days), and LPS1+SD groups. Cytokine levels were measured using an enzyme-linked immunosorbent assay (ELISA). RESULTS: Based on the results, the LPS1+SD group showed increased total distance and escape latency compared to the other groups in the MWM test. Besides, the LPS1+SD group exhibited a significant decrease in long-term potentiation (LTP) induction and maintenance in the CA1 area of the brain. Finally, the inflammatory cytokine interleukin-1ß (IL-1ß) levels were significantly higher in the LPS1+SD group than in the Saline group. CONCLUSION: These findings suggest that the combined effects of SD and brain inflammatory response can have more harmful effects on cognitive function, LTP, and inflammatory factors than either SD or LPS1 alone.

Sleep loss and emotion: A systematic review and meta-analysis of over 50 years of experimental research.

In a largely sleep-deprived society, quantifying the effects of sleep loss on emotion is critical for promoting psychological health. This preregistered systematic review and meta-analysis quantified the effects of various forms of sleep loss on multiple aspects of emotional experiences. Eligible studies used experimental reductions of sleep via total sleep deprivation, partial sleep restriction, or sleep fragmentation in healthy populations to examine effects on positive affect, negative affect, general mood disturbances, emotional reactivity, anxiety symptoms, and/or depressive symptoms. In total, 1,338 effect sizes across 154 studies were included (N = 5,717; participant age range = 7-79 years). Random effects models were conducted, and all forms of sleep loss resulted in reduced positive affect (standardized mean difference [SMD] = -0.27 to -1.14), increased anxiety symptoms (SMD = 0.57-0.63), and blunted arousal in response to emotional stimuli (SMD = -0.20 to -0.53). Findings for negative affect, reports of emotional valence in response to emotional stimuli, and depressive symptoms were mixed and depended on the type of sleep loss. Nonlinear effects for the amount of sleep loss as well as differences based on the stage of sleep restricted (i.e., rapid eye movement sleep or slow-wave sleep) were also detected. This study represents the most comprehensive quantitative synthesis of experimental sleep and emotion research to date and provides strong evidence that periods of extended wakefulness, shortened sleep duration, and/or nighttime awakenings adversely influence human emotional functioning. Findings provide an integrative foundation for future research on sleep and emotion and elucidate the precise ways that inadequate sleep may impact our daytime emotional lives. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sleep Duration and Executive Function in Adults.

PURPOSE OF REVIEW: To review the literature examining the relationship between sleep and cognition, specifically examining the sub-domain of executive function. We explore the impact of sleep deprivation and the important question of how much sleep is required for optimal cognitive performance. We consider how other sleep metrics, such as sleep quality, may be a more meaningful measure of sleep. We then discuss the putative mechanisms between sleep and cognition followed by their contribution to developing dementia. RECENT FINDINGS: Sleep duration and executive function display a quadratic relationship. This suggests an optimal amount of sleep is required for daily cognitive processes. Poor sleep efficiency and sleep fragmentation are linked with poorer executive function and increased risk of dementia during follow-up. Sleep quality may therefore be more important than absolute duration. Biological mechanisms which may underpin the relationship between sleep and cognition include brain structural and functional changes as well as disruption of the glymphatic system. Sleep is an important modifiable lifestyle factor to improve daily cognition and, possibly, reduce the risk of developing dementia. The impact of optimal sleep duration and sleep quality may have important implications for every ageing individual.

Exercise to prevent the negative effects of sleep deprivation: A systematic review and meta-analysis.

Ample sleep is an important basis for maintaining health, however with the pace of life accelerating in modern society, more people are using sacrificial sleep to cope with these social changes. Sleep deprivation can have negative effects on cognitive performance and psychosomatic health. It is well known that exercise, as a beneficial intervention strategy for human health, has been increasingly used in the clinic. But it's not clear if it can prevent the negative effects of sleep deprivation. In this meta-analysis, we reviewed 23 articles from PubMed and Web of Science to investigate whether moderate physical exercise can prevent the negative effects of sleep deprivation in rodents. Our findings suggest that exercise can prevent sleep deprivation-induced cognitive impairment and anxiety-like behaviors through multiple pathways. We also discuss possible molecular mechanisms involved in this protective effect, highlighting the potential of exercise as a preventive or therapeutic strategy for sleep deprivation-induced negative effects.

The effect of fragmented sleep on emotion regulation ability and usage.

Sleep has a profound effect on our mood, but insight in the mechanisms underlying this association is still lacking. We tested whether emotion regulation is a mediator in the relationship between fragmented sleep and mood disturbance. The effect of fragmented sleep on the emotion regulation strategies, including cognitive reappraisal, distraction, acceptance and suppression ability, was assessed. We further tested whether the use of these strategies, as well as rumination and self-criticism, mediated the association between fragmented sleep and negative and positive affect. Participants (N = 69) wore an actiwatch and filled in a sleep diary for 12 consecutive nights. They had one control night and one sleep fragmentation night. Emotion regulation ability was assessed with an experimental task. Usage of emotion regulation strategies and negative and positive affect were assessed four times during the day with a survey after the control and sleep fragmentation night. Cognitive reappraisal, distraction, acceptance and suppression ability did not differ between the sleep fragmentation and control condition. However, participants reported higher usage of rumination and distraction after the sleep fragmentation night and rumination significantly mediated the negative association between fragmented sleep and negative affect.

Relationship between sleep disturbance and burnout among Chinese urban teachers: Moderating roles of resilience.

BACKGROUND: Sleep disturbance and burnout are prevalent among primary and secondary school teachers. Nevertheless, little is known about the relationship between sleep disturbance and burnout, and the mechanisms connecting this link. Our study aimed to explore the relationship between sleep disturbance and burnout among urban teachers, as well as to investigate this influencing mechanism further with resilience as a moderator. METHODS: 14,218 primary and secondary school teachers provided valid data. We assessed demographic information, sleep disturbance, burnout, and resilience. Multivariable logistic regression, Spearman correlation, and moderation analyses were used to evaluate the relationship between sleep disturbance and burnout and the moderating role of resilience. RESULTS: Of the participants, the prevalence of sleep disturbance and sleep deprivation among teachers was 20.0% and 31.7%, respectively. Additionally, 58.4% of teachers reported moderate or severe burnout, and 15.3% had both sleep disturbance and burnout. Sleep disturbance was significant and positively related to burnout. Resilience was found to moderate the association between sleep disturbance and burnout. CONCLUSIONS: These findings suggested strong associations between sleep disturbance and burnout. Interventions in improving resilience may protect teachers with sleep disturbance from burnout.

Assessing the impact of sleep restriction on the attention and executive functions of medical students: a prospective cohort study.

OBJECTIVE: To compare the performance of medical students regarding attention and executive functions during a period of sleep restriction (insufficient sleep; period of classes) and a period of free sleep (sufficient sleep; vacation period). BACKGROUND: Sleep deprivation is associated with poor academic outcomes. Few studies have assessed the cognitive changes associated with sleep deprivation due to insufficient sleep syndrome in students and how they occur in real-life situations. METHODS: This was a prospective cohort study. Medical students were assessed at two moments (class and vacation). The interval between assessments was 30 days. The Pittsburgh Sleep Quality Index, the Consensus Sleep Diary, the Montreal Cognitive Assessment, the Psychomotor Vigilance Test (PVT) and the Wisconsin Sorting Cards Test were used. RESULTS: Forty-one students were assessed, 49% were female, with a median age of 21 (20; 23) years. There was a lower number of hours slept (5.75 (5.4; 7.0) vs 7.33 (6.0; 8.0) hours; p = 0.037), and a significantly poorer performance in the PVT (mean reaction time, p = 0.005; Minor lapses, p = 0.009) during the period of classes when compared to the vacation period. There was a correlation between the variation in hours of sleep of the two assessments and a variation in minor lapses in the two assessments (Ro: -0.395; p = 0.011; Spearman's correlation). CONCLUSIONS: Students had fewer hours of sleep and more reduced attention during the period of classes than during the vacation period. This decrease in sleeping hours was correlated with more impaired attention.

The consequences of sleep deprivation on cognitive performance.

Although not fully understood, sleep is accepted as a vital and organized sequence of events that follows a regular cyclic program each night to ensure the human body can perform at its optimum. A lack of sleep, or sleep deprivation (SD), is a widespread phenomenon that can induce adverse changes in cognitive performance. This review focused on the biological explanation as well as the research investigating the numerous effects that SD can have on cognition. A reduction in sleep does not occur independently of the effects on memory, attention, alertness, judgment, decision-making, and overall cognitive abilities in the brain, resulting in decreased function and impaired cognitive performance.

Sleep restriction effects on sleep spindles in adolescents and relation of these effects to subsequent daytime sleepiness and cognition.

STUDY OBJECTIVES: Limiting spindle activity via sleep restriction could explain some of the negative cognitive effects of sleep loss in adolescents. The current study evaluates how sleep restriction affects sleep spindle number, incidence, amplitude, duration, and wave frequency and tests whether sleep restriction effects on spindles change across the years of adolescence. The study determines whether sleep restriction effects on daytime sleepiness, vigilance, and cognition are related to changes in sleep spindles. METHODS: In each year of this 3-year longitudinal study, 77 participants, ranging in age from 10 to 16 years, each completed three different time in bed (TIB) schedules: 7, 8.5, or 10 hours in bed for 4 consecutive nights. A computer algorithm detected and analyzed sleep spindles in night four central and frontal electroencephalogram. Objective and self-reported daytime sleepiness and cognition were evaluated on the day following the 4th night. RESULTS: For 7 versus 10 hours TIB average all-night frontal and central spindle counts were reduced by 35% and 32%, respectively. Reducing TIB also significantly decreased spindle incidence in the first 5 hours of non-rapid eye movement sleep, produced small but significant reductions in spindle amplitude, and had little to no effect on spindle duration and spindle wave frequency. Sleep restriction effects did not change with age. The reductions in spindle count and incidence were related to daytime sleepiness on the following day but were not related to working memory. CONCLUSIONS: The sleep loss effects on daytime functioning in adolescents are partially mediated by reduced sleep spindles impacting daytime sleepiness.

[Research Progress in the Effect of Sleep Deprivation on Working Memory and Its Mechanisms].

The incidence of sleep deprivation is increasing year by year and people are also paying more attention to the effects of sleep deprivation on the human body and on cognition. In addition, working memory is the foundation of many advanced cognitive functions. Therefore, we reviewed, herein, the relevant research literature on the influence of sleep deprivation on working memory, the relevant influencing factors, and possible mechanisms of action, intending to acquire a more thorough understanding of the effects of sleep deprivation on working memory and to provide evidence for scientific and sound strategies of sleep.

Insomnia-A Systematic Review and Comparison of Medical Resident's Average Off-Call Sleep Times.

Sleep deprivation is known to have serious consequences, including a decrease in performance, attention and neurocognitive function. It seems common knowledge that medical residents are routinely sleep deprived, yet there is little objective research recording their average sleep times. To discern whether residents may be suffering from the abovementioned side effects, this review aimed to analyze their average sleep times. Thirty papers recording the average sleep time of medical residents were found via a literature search using the key words "resident" and "sleep". An analysis of the mean sleep times cited therein revealed a range of sleep from 4.2 to 8.6 h per night, the median being 6.2 h. A sub-analysis of papers from the USA showed barely any significant differences in sleep time between the specialties, but the mean sleep times were below 7 h. The only significant difference (p = 0.039) was between the mean sleep times of pediatric and urology residents, with the former achieving less sleep. The comparison of methods for data collection showed no significant difference in the sleep times collected. The results of this analysis imply that residents are regularly sleep deprived and may therefore suffer from the abovementioned consequences.

The effect of a 2 week ketogenic diet, versus a carbohydrate-based diet, on cognitive performance, mood and subjective sleepiness during 36 h of extended wakefulness in military personnel: An exploratory study.

Extended wakefulness, or sleep deprivation, impairs cognitive performance and brain glucose metabolism. A ketogenic diet (KD) provides an alternative fuel source, ketone bodies, that could elicit a metabolic benefit during sleep deprivation. A randomised, cross-over trial was conducted with seven male military personnel. Participants ingested an iso-energetic ketogenic diet or carbohydrate-based diet for 14 days, immediately followed by 36 h of extended wakefulness and separated by a 12 day washout. Cognitive performance, mood, subjective sleepiness, capillary blood glucose, and D-ß-hydroxybutyrate concentrations were measured every 2 h during extended wakefulness. Linear mixed models were used to analyse data. D-ß-hydroxybutyrate was higher (p < 0.001) and glucose was lower (p < 0.01) on the KD compared with the carbohydrate-based diet. The KD improved psychomotor vigilance task performance (number of lapses, mean reciprocal response time, mean fastest 10% response time (RT), and mean slowest 10% RT; all p < 0.05), running memory continuous performance test performance (RT and number of correct responses per minute; both p < 0.01), and vigour, fatigue, and sleepiness (all, p ≤ 0.001) compared with the carbohydrate-based diet. In conclusion, a KD demonstrated beneficial effects on cognitive performance, mood, and sleepiness during 36 h of extended wakefulness compared with a carbohydrate-based diet.

A narrative review of the impact of work hours and insufficient rest on job performance.

OBJECTIVE: This review discusses the scientific evidence regarding effects of insufficient rest on clinical performance and house officer training programs, the associations of clinical duty scheduling with insufficient rest, and the implications for risk management. STUDY DESIGN: Narrative review. METHODS: Several literature searches using broad terms such as "sleep deprivation," "veterinary," "physician," and "surgeon" were performed using PubMed and Google scholar. RESULTS: Sleep deprivation and insufficient rest have clear and deleterious effects on job performance, which in healthcare occupations impacts patient safety and practice function. The unique requirements of a career in veterinary surgery, which may include on-call shifts and overnight work, can lead to distinct sleep challenges and chronic insufficient rest with resultant serious but often poorly recognized impacts. These effects negatively impact practices, teams, surgeons, and patients. The self-assessment of fatigue and performance effect is demonstrably untrustworthy, reinforcing the need for institution-level protections. While the issues are complex and there is no one-size-fits-all approach, duty hour or workload restrictions may be an important first step in addressing these issues within veterinary surgery, as it has been in human medicine. CONCLUSION: Systematic re-examination of cultural expectations and practice logistics are needed if improvement in working hours, clinician well-being, productivity, and patient safety are to occur. CLINICAL SIGNIFICANCE (OR IMPACT): A more comprehensive understanding of the magnitude and consequence of sleep-related impairment better enables surgeons and hospital management to address systemic challenges in veterinary practice and training programs.

Total Sleep Deprivation Increases Brain Age Prediction Reversibly in Multisite Samples of Young Healthy Adults.

Sleep loss pervasively affects the human brain at multiple levels. Age-related changes in several sleep characteristics indicate that reduced sleep quality is a frequent characteristic of aging. Conversely, sleep disruption may accelerate the aging process, yet it is not known what will happen to the age status of the brain if we can manipulate sleep conditions. To tackle this question, we used an approach of brain age to investigate whether sleep loss would cause age-related changes in the brain. We included MRI data of 134 healthy volunteers (mean chronological age of 25.3 between the age of 19 and 39 years, 42 females/92 males) from five datasets with different sleep conditions. Across three datasets with the condition of total sleep deprivation (>24 h of prolonged wakefulness), we consistently observed that total sleep deprivation increased brain age by 1-2 years regarding the group mean difference with the baseline. Interestingly, after one night of recovery sleep, brain age was not different from baseline. We also demonstrated the associations between the change in brain age after total sleep deprivation and the sleep variables measured during the recovery night. By contrast, brain age was not significantly changed by either acute (3 h time-in-bed for one night) or chronic partial sleep restriction (5 h time-in-bed for five continuous nights). Together, the convergent findings indicate that acute total sleep loss changes brain morphology in an aging-like direction in young participants and that these changes are reversible by recovery sleep.SIGNIFICANCE STATEMENT Sleep is fundamental for humans to maintain normal physical and psychological functions. Experimental sleep deprivation is a variable-controlling approach to engaging the brain among different sleep conditions for investigating the responses of the brain to sleep loss. Here, we quantified the response of the brain to sleep deprivation by using the change of brain age predictable with brain morphologic features. In three independent datasets, we consistently found increased brain age after total sleep deprivation, which was associated with the change in sleep variables. Moreover, no significant change in brain age was found after partial sleep deprivation in another two datasets. Our study provides new evidence to explain the brainwide effect of sleep loss in an aging-like direction.

Sleep in Residents: A Comparison between Anesthesiology and Occupational Medicine Interns.

Sleep deprivation is a significant risk to the health and judgment of physicians. We wanted to investigate whether anesthesiology residents (ARs) who work only one night shift per week have different physical and mental health from occupational medicine residents (OMRs) who do not work at night. A total of 21 ARs and 16 OMRs attending a university general hospital were asked to wear an actigraph to record sleep duration, heart rate and step count and to complete a questionnaire for the assessment of sleep quality, sleepiness, fatigue, occupational stress, anxiety, depression and happiness. ARs had shorter sleep duration than OMRs; on average, they slept 1 h and 20 min less (p < 0.001). ARs also had greater daytime sleepiness, a higher heart rate and lower happiness than OMRs. These results should be interpreted with caution given the cross-sectional nature of the study and the small sample size, but they are an incentive to promote sleep hygiene among residents.

The effect of sleep continuity disruption on multimodal emotion processing and regulation: a laboratory-based, randomised, controlled experiment in good sleepers.

Previous research shows that experimental sleep deprivation alters emotion processing, suggesting a potential mechanism linking sleep disruption to mental ill-health. Extending previous work, we experimentally disrupted sleep continuity in good sleepers and assessed next-day emotion processing and regulation using tasks with established sensitivity to depression. In a laboratory-based study, 51 good sleepers (37 female; mean [SD] age 24 [3.63] years), were randomised to 1 night of uninterrupted sleep (n = 24) or sleep continuity disruption (n = 27). We assessed emotion perception, attention, and memory the following day. Participants also completed an emotion regulation task and measures of self-reported affect, anxiety, sleepiness, overnight declarative memory consolidation, and psychomotor vigilance. Confirming the effects of the manipulation, sleep continuity disruption led to a marked decrease in polysomnography-defined total sleep time (229.98 versus 434.57 min), increased wake-time after sleep onset (260.66 versus 23.84 min), and increased sleepiness (d = 0.81). Sleep continuity disruption led to increased anxiety (d = 0.68), decreased positive affect (d = -0.62), reduced overnight declarative memory consolidation (d = -1.08), and reduced psychomotor vigilance (longer reaction times [d = 0.64] and more lapses [d = 0.74]), relative to control. However, contrary to our hypotheses, experimental sleep disruption had no effect on perception of, or bias for, emotional facial expressions, emotional memory for words, or emotion regulation following worry induction. In conclusion, 1 night of sleep continuity disruption had no appreciable effect on objective measures of emotion processing or emotion regulation in response to worry induction, despite clear effects on memory consolidation, vigilance, and self-reported affect and anxiety.

Effects of total sleep deprivation on components of top-down attentional control using a flexible attentional control task.

Sleep deprivation consistently decreases vigilant attention, which can lead to difficulty in performing a variety of cognitive tasks. However, sleep-deprived individuals may be able to compensate for degraded vigilant attention by means of top-down attentional control. We employed a novel task to measure the degree to which individuals overcome impairments in vigilant attention by using top-down attentional control, the Flexible Attentional Control Task (FACT). The FACT is a two-choice task that has trials with valid, invalid, and neutral cues, along with an unexpected switch in the probability of cue validity about halfway in the task. The task provides indices that isolate performance components reflecting vigilant attention and top-down attentional control. Twelve healthy young adults completed an in-laboratory study. After a baseline day, the subjects underwent 39 hours of total sleep deprivation (TSD), followed by a recovery day. The FACT was administered at 03:00, 11:00, and 19:00 during sleep deprivation (TSD condition) and at 11:00 and 19:00 after baseline sleep and at 11:00 after recovery sleep (rested condition). When rested, the subjects demonstrated both facilitation and interference effects on cued trials. While sleep deprived, the subjects showed vigilant attention deficits on neutral cue trials, and an impaired ability to reduce these deficits by using predictive contextual cues. Our results indicate that the FACT can dissociate vigilant attention from top-down attentional control. Furthermore, they show that during sleep deprivation, contextual cues help individuals to compensate partially for impairments in vigilant attention, but the effectiveness of top-down attentional control is diminished.

Intelligence predicts better cognitive performance after normal sleep but larger vulnerability to sleep deprivation.

Fluid intelligence is seen as a beneficial attribute, protecting against stress and ill-health. Whether intelligence provides resilience to the cognitive effects of insufficient sleep was tested in the current pre-registered experimental study. Participants (N = 182) completed the Raven's test (measuring fluid intelligence) and a normal night of sleep or a night of total sleep deprivation. Sleepiness and four cognitive tests were completed at 22:30 hours (baseline), and the following day after sleep manipulation. At baseline, higher fluid intelligence was associated with faster and more accurate arithmetic calculations, and better episodic memory, but not with spatial working memory, simple attention or sleepiness. Those with higher fluid intelligence were more, not less, impacted by sleep deprivation, evident for arithmetic ability, episodic memory and spatial working memory. We need to establish a more nuanced picture of the benefits of intelligence, where intelligence is not related to cognitive advantages in all situations.