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Mindaugas Jurgelis,1,2 Johanna M Boardman,1,2 James P Coxon,1,2 Sean PA Drummond,1,2 Trevor TJ Chong1– 4 1Turner Institute for Brain and Mental Health, Monash University, Melbourne, Victoria, 3800, Australia; 2School of Psychological Sciences, Monash University, Melbourne, Victoria, 3800, Australia; 3Department of Neurology, Alfred Health, Melbourne, Victoria, 3004, Australia; 4Department of Clinical Neurosciences, St Vincent’s Hospital, Melbourne, Victoria, 3065, AustraliaCorrespondence: Mindaugas Jurgelis, Tel +61 491 020 830, Email m.k.jurgelis@gmail.com Trevor TJ Chong, Tel +61 3 9902 4222, Email trevor.chong@monash.eduPurpose: Motivation is an important driver of behaviour, and several frameworks distinguish the willingness of individuals to invest cognitive versus physical effort to achieve a goal. One outstanding question is whether sleep loss lowers motivation within specific domains of effort, or has a global effect on motivation across multiple domains. Here, we investigated the effects of sleep restriction on the motivation to invest cognitive or physical effort in return for reward.Materials and Methods: 24 healthy young adults (11 females) completed an effort-based decision-making task over two laboratory sessions – once while sleep restricted (three consecutive nights with a three-hour sleep opportunity), and the other while fully rested (nine-hour sleep opportunity on each night). In an initial reinforcement phase, participants were trained to ceiling performance across six levels of effort on separate cognitively and physically demanding tasks. Then, in the critical decision-making phase, participants revealed their preference for how much cognitive or physical effort they would be willing to invest for reward.Results: Sleep restriction reduced the willingness to exert cognitive effort, but spared motivation in the physical domain. Furthermore, the reduction in cognitive motivation appeared to be a primary motivational deficit, which could not be attributed to differences in reward-likelihood of different levels of effort or the temporal structure of the task.Conclusion: The results suggest that sleep restriction has a selective effect on cognitive over physical motivation, which has significant implications for real-world settings in which individuals must maintain high levels of cognitive motivation in the face of chronic sleep loss.Keywords: sleep loss, cognitive effort, physical effort, effort-based decision-making

Rationale: Healthy aging is associated with cognitive deficits similar to those found in obstructive sleep apnea (OSA). As in OSA, older adults show compensatory cerebral activation during cognitive demands in the face of neurocognitive decline.Objectives: The current study examines whether the combination of increasing age and sleep apnea will lead to a stronger compensatory response than either factor alone, or overwhelm the brain's capacity to compensate.Methods: A total of 14 treatment-naive patients with sleep apnea (aged 25-59 yr) and 14 age-matched healthy control subjects were each divided into two age groups of young (<45 yr) and middle-aged (> or = 45 yr). All underwent a sleep study, followed the next morning by a functional magnetic resonance imaging session that included a sustained attention and a verbal encoding task. A priori contrast analyses compared middle-aged patients with OSA to young patients, young control subjects, and middle-aged control subjects.Measurements and Main Results: Middle-aged patients with OSA showed reduced performance for immediate word recall and slower reaction time during sustained attention compared with the other three groups (middle-aged control, young sleep apnea, and young control). For both tasks, decreased activation was detected for middle-aged sleep apnea relative to the other groups in task-related brain regions.Conclusions: These results suggest that the presence of both sleep apnea and increasing age overwhelmed the brain's capacity to respond to cognitive challenges with compensatory recruitment and to maintain performance. The findings that sleep apnea impairs performance and brain function at a younger age than what might ordinarily be expected underscore the importance of early diagnosis and treatment of sleep apnea. [ABSTRACT FROM AUTHOR]

The inter-alpha-trypsin inhibitor (IαI) complex is composed of the bikunin core protein with a single chondroitin sulfate (CS) attached and one or two heavy chains (HCs) covalently linked to the CS chain. The HCs from IαI can be transferred to hyaluronan (HA) through a TNFα-stimulated gene-6 (TSG-6) dependent process to form an HC•HA matrix. Previous studies reported increased IαI, HA, and HC•HA complexes in mouse bronchoalveolar lavage fluid (BALF) post-influenza infection. However, the expression and incorporation of HCs into the HA matrix of the lungs during the clinical course of influenza A virus (IAV) infection and the biological significance of the HC•HA matrix are poorly understood. The present study aimed to better understand the composition of HC•HA matrices in mice infected with IAV and how these matrices regulate the host pulmonary immune response. In IAV infected mice bikunin, HC1-3, TSG-6, and HAS1-3 all show increased gene expression at various times during a 12-day clinical course. The increased accumulation of IαI and HA was confirmed in the lungs of infected mice using immunohistochemistry and quantitative digital pathology. Western blots confirmed increases in the IαI components in BALF and lung tissue at 6 days post-infection (dpi). Interestingly, HCs and bikunin recovered from BALF and plasma from mice 6 dpi with IAV, displayed differences in the HC composition by Western blot analysis and differences in bikunin's CS chain sulfation patterns by mass spectrometry analysis. This strongly suggests that the IαI components were synthesized in the lungs rather than translocated from the vascular compartment. HA was significantly increased in BALF at 6 dpi, and the HA recovered in BALF and lung tissues were modified with HCs indicating the presence of an HC•HA matrix. In vitro experiments using polyinosinic-polycytidylic acid (poly(I:C)) treated mouse lung fibroblasts (MLF) showed that modification of HA with HCs increased cell-associated HA, and that this increase was due to the retention of HA in the MLF glycocalyx. In vitro studies of leukocyte adhesion showed differential binding of lymphoid (Hut78), monocyte (U937), and neutrophil (dHL60) cell lines to HA and HC•HA matrices. Hut78 cells adhered to immobilized HA in a size and concentration-dependent manner. In contrast, the binding of dHL60 and U937 cells depended on generating a HC•HA matrix by MLF. Our in vivo findings, using multiple bronchoalveolar lavages, correlated with our in vitro findings in that lymphoid cells bound more tightly to the HA-glycocalyx in the lungs of influenza-infected mice than neutrophils and mononuclear phagocytes (MNPs). The neutrophils and MNPs were associated with a HC•HA matrix and were more readily lavaged from the lungs. In conclusion, this work shows increased IαI and HA accumulation and the formation of a HC•HA matrix in mouse lungs post-IAV infection. The formation of HA and HC•HA matrices could potentially create specific microenvironments in the lungs for immune cell recruitment and activation during IAV infection., Competing Interests: Declaration of competing interest The authors declare no competing financial interests. AJD and CMM are founders of Link Biologics Limited, that is developing a TSG-6-based biological drug, and AJD, CMM and SPD are shareholders in the company., (Copyright © 2024. Published by Elsevier B.V.)

Objective: To investigate the role of endogenous TSG-6 in human osteoarthritis (OA) and assess the disease-modifying potential of a TSG-6-based biological treatment in cell, explant and animal models of OA., Design: Knee articular cartilages from OA patients were analyzed for TSG-6 protein and mRNA expression using immunohistochemistry and RNAscope, respectively. The inhibitory activities of TSG-6 and its isolated Link module (Link&#95;TSG6) on cytokine-induced degradation of OA cartilage explants were compared. Human mesenchymal stem/stromal cell-derived chondrocyte pellet cultures were used to determine the effects of Link&#95;TSG6 and full-length TSG-6 on IL-1α-, IL-1β-, or TNF-stimulated ADAMTS4, ADAMTS5, and MMP13 mRNA expression. Link&#95;TSG6 was administered i.a. to the rat ACLTpMMx model; cartilage damage and tactile allodynia were assessed., Results: TSG-6 is predominantly associated with chondrocytes in regions of cartilage damage where high TSG-6 expression aligns with low MMP13, the major collagenase implicated in OA progression. Link&#95;TSG6 is more potent than full-length TSG-6 at inhibiting cytokine-mediated matrix breakdown in human OA cartilage explants;>50% of donor cartilages, from 59 tested, were responsive to Link&#95;TSG6 treatment. Link&#95;TSG6 also displayed more potent effects in 3D pellet cultures, suppressing ADAMTS4, ADAMTS5, and MMP13 gene expression, which was consistent with reduced aggrecanase and collagenase activities in explant cultures. Link&#95;TSG6 treatment reduced touch-evoked pain behavior and dose-dependently inhibited cartilage damage in a rodent model of surgically-induced OA., Conclusions: Link&#95;TSG6 has enhanced chondroprotective activity compared to the full-length TSG-6 protein and shows potential as a disease modifying OA drug via its inhibition of aggrecanase and collagenase activity., Competing Interests: Declaration of Competing Interest AJD and CMM are founders of Link Biologics Limited and AJD, CMM, SPD, JLS and NK are shareholders in the company., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background and Aims: Perianal fistula represents one of the most disabling manifestations of Crohn's disease (CD) due to complete destruction of the affected mucosa, which is replaced by granulation tissue and associated with changes in tissue organization. To date, the molecular mechanisms underlying perianal fistula formation are not well defined. Here, we dissected the tissue changes in the fistula area and addressed whether a dysregulation of extracellular matrix (ECM) homeostasis can support fistula formation., Methods: Surgical specimens from perianal fistula tissue and the surrounding region of fistulizing CD were analyzed histologically and by RNA sequencing. Genes significantly modulated were validated by real-time polymerase chain reaction, Western blot, and immunofluorescence assays. The effect of the protein product of TNF-stimulated gene-6 (TSG-6) on cell morphology, phenotype, and ECM organization was investigated with endogenous lentivirus-induced overexpression of TSG-6 in Caco-2 cells and with exogenous addition of recombinant human TSG-6 protein to primary fibroblasts from region surrounding fistula. Proliferative and migratory assays were performed., Results: A markedly different organization of ECM was found across fistula and surrounding fistula regions with an increased expression of integrins and matrix metalloproteinases and hyaluronan (HA) staining in the fistula, associated with increased newly synthesized collagen fibers and mechanosensitive proteins. Among dysregulated genes associated with ECM, TNFAI6 (gene encoding for TSG-6) was as significantly upregulated in the fistula compared with area surrounding fistula, where it promoted the pathological formation of complexes between heavy chains from inter-alpha-inhibitor and HA responsible for the formation of a crosslinked ECM. There was a positive correlation between TNFAI6 expression and expression of mechanosensitive genes in fistula tissue. The overexpression of TSG-6 in Caco-2 cells promoted migration, epithelial-mesenchymal transition, transcription factor SNAI1, and HA synthase (HAs) levels, while in fibroblasts, isolated from the area surrounding the fistula, it promoted an activated phenotype. Moreover, the enrichment of an HA scaffold with recombinant human TSG-6 protein promoted collagen release and increase of SNAI1, ITGA4, ITGA42B, and PTK2B genes, the latter being involved in the transduction of responses to mechanical stimuli., Conclusions: By mediating changes in the ECM organization, TSG-6 triggers the epithelial-mesenchymal transition transcription factor SNAI1 through the activation of mechanosensitive proteins. These data point to regulators of ECM as new potential targets for the treatment of CD perianal fistula., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Cognitive behavioral therapy for insomnia (CBT-I) has been shown to be efficacious and now is considered the first-line treatment for insomnia for both uncomplicated insomnia and insomnia that occurs comorbidly with other chronic disorders (comorbid insomnia). The purposes of this review are to provide a comprehensive summary of the efficacy data (for example, efficacy overall and by clinical and demographic considerations and by CBT-I formulation) and to discuss the future of CBT-I (for example, what next steps should be taken in terms of research, dissemination, implementation, and practice)., Competing Interests: The authors declare that they have no competing interests.No competing interests were disclosed.No competing interests were disclosed.No competing interests were disclosed., (Copyright: © 2022 Perlis ML et al.)

Background: Anxiety and depression are commonly comorbid with sleep problems. Despite growing acknowledgement that bedpartners are important determinants of sleep quality, few studies have explored mental health as a risk factor for disrupted sleep of the bedpartner. We examined whether anxiety or depression symptoms predicted an individual's sleep or their bedpartner's sleep, in couples where one partner experienced insomnia and in couples without sleep disorders., Methods: Fifty-two bed-sharing couples where one individual had insomnia ("Patient"), and 55 non-sleep-disordered couples completed the Beck Anxiety Inventory, Patient Health Questionnaire-9, and Insomnia Severity Index (ISI). Sleep was monitored for seven nights. Actor-Partner Interdependence Models assessed whether anxiety or depression symptoms predicted individual or dyadic sleep (wake transmission)., Results: Greater anxiety symptoms predicted increased vulnerability to being woken by their bedpartner, as well as increased frequency of waking their bedpartner up during the night in Patients with insomnia, but not in non-sleep-disordered couples. Neither anxiety nor depression symptoms predicted an individual's or their bedpartner's sleep efficiency in either subsample. However, ISI was positively predicted by own anxiety and depression symptoms for Patients with insomnia and in non-sleep-disordered couples., Limitations: The non-sleep-disordered subsample experienced only mild symptoms of anxiety and depression, potentially reducing predictive power., Conclusions: Anxiety may help reveal social determinants of sleep in couples experiencing insomnia. These data underscore the importance of considering sleep, the bedpartner, and affective symptoms in mental health and sleep assessments., Competing Interests: Declaration of Competing Interest The authors have nothing to disclose on receipt of financial support for the research, authorship, and/or publication of this article. EMW, KH, and PJN have no conflicts of interest to declare. The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. SPAD serves on a DSMB for Zelda Therapeutics Limited, he has provided consulting to Pfizer, Inc., and serves as a primary investigator on two grants from the US Department of Defense. AJKP serves as an investigator on the Alertness Safety and Productivity Cooperative Research Centre (CRC) and has received funding from Beacon Lighting., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Chronic sleep restriction (SR) increases sleepiness, negatively impacts mood, and impairs a variety of cognitive performance measures. The vast majority of work establishing these effects are tightly controlled in-lab experimental studies. Examining commonly-experienced levels of SR in naturalistic settings is more difficult and generally involves observational methods, rather than active manipulations of sleep. The same is true for analyzing behavioral and cognitive outcomes at circadian unfavorable times. The current study tested the ability of an at-home protocol to manipulate sleep schedules (i.e., impose SR), as well as create a mismatch between a subject's circadian preference and time of testing. Viability of the protocol was assessed via completion, compliance with the SR, and success at manipulating sleepiness and mood. An online survey was completed by 3630 individuals to assess initial eligibility, 256 agreed via email response to participate in the 3-week study, 221 showed for the initial in-person session, and 184 completed the protocol (175 with complete data). The protocol consisted of 1 week at-home SR (5-6 hours in bed/night), 1 week wash-out, and 1 week well-rested (WR: 8-9 hours in bed/night). Sleep was monitored with actigraphy, diary, and call-ins. Risk management strategies were implemented for subject safety. At the end of each experimental week, subjects reported sleepiness and mood ratings. Protocol completion was 83%, with lower depression scores, higher anxiety scores, and morning session assignment predicting completion. Compliance with the sleep schedule was also very good. Subjects spent approximately 2 hours less time in bed/night and obtained an average of 1.5 hours less nightly sleep during SR, relative to WR, with 82% of subjects obtaining at least 60 minutes less average nightly sleep. Sleepiness and mood were impacted as expected by SR. These findings show the viability of studying experimental chronic sleep restriction outside the laboratory, assuming appropriate safety precautions are taken, thus allowing investigators to significantly increase ecological validity over strictly controlled in-lab studies.

Many critical decisions require evaluation of accumulated previous information and/or newly acquired evidence. Although neural correlates of belief updating have been investigated, how these neural processes guide decisions involving Bayesian choice is less clear. Here, we used functional MRI to investigate neural activity during a Bayesian choice task involving two sources of information: base rate odds ('odds') and sample evidence ('evidence'). Thirty-seven healthy control individuals performed the Bayesian choice task in which they had to make probability judgements. Average functional MRI activity during the trials where choice was consistent with use of Odds, use of Evidence, and use of Both was compared. Decision-making consistent with odds, evidence and both each strongly activated the bilateral executive network encompassing the bilateral frontal, cingulate, posterior parietal and occipital cortices. The Evidence consistent, compared with Odds consistent, decisions showed greater activity in the bilateral middle and inferior frontal and right lateral occipital cortices. Decisions consistent with the use of Both strategies were associated with increased activity in the bilateral middle frontal and superior frontal cortices. These findings support the conclusion that both overlapping and distinct brain regions within the frontoparietal network underlie the incorporation of different types of information into a Bayesian decision.

This study examines whether voluntary sleep restriction at commonly experienced levels impacts decision making in a Bayesian choice task. Participants recruited were largely traditional age college students from a regional state university (n = 100) and a federal military academy (n = 99; n = 56 and 43, respectively, used in final analysis). Sleep was measured by actigraphy over a one-week period, followed by performance of a decision task. The task involved two sources of information, base rate odds and sample evidence, with subjects asked to make a probability judgment. Results found that subjects with nightly sleep < 6 hr (sleep deprived = SD), relative to those with > 7 hr, placed less decision weight on new evidence, relative to base rate information, in making difficult choices. This result is strongest among female subjects. For easier choices, voluntary SD did not affect relative decision weights placed on the two sources of available information.

Study Objectives: Portable and automated sleep monitoring technology is becoming widely available to consumers, and one wireless system (WS) has recently surfaced as a research tool for sleep and sleep staging assessment outside the hospital/laboratory; however, previous research findings indicate low sensitivity for wakefulness detection. Because difficulty discriminating between wake and sleep is likely to affect staging performance, we sought to further evaluate the WS by comparing it to the gold-standard polysomnography (PSG) and actigraphy (ACT) for overall sleep/wakefulness detection and sleep staging, within high and low sleep efficiency sleepers., Methods: Twenty-nine healthy adults (eight females) underwent concurrent WS, PSG, and ACT assessment in an overnight laboratory study. Epoch-by-epoch agreement was determined by comparing sleep/wakefulness decisions between the WS to both PSG and ACT, and for detection of light, deep, and rapid eye movement (REM) sleep stages between the WS and PSG., Results: Sensitivity for wakefulness was low (40%), and an overestimation of total sleep time and underestimation of wake after sleep onset was observed. Prevalence and bias adjusted kappa statistic indicated moderate-to-high agreement between the WS and PSG for sleep staging. However, upon further inspection, WS performance varied by sleep efficiency, with the best performance during high sleep efficiency., Conclusions: The benefit of the WS as a sleep monitoring device over ACT is the ability to assess sleep stages, and our findings suggest this benefit is only realized within high sleep efficiency. Care should be taken to collect data under conditions where this is expected., (© 2016 American Academy of Sleep Medicine.)

Study Objectives: There is limited information about prevalence of insomnia in general populations of veterans of recent wars in Iraq and Afghanistan. No studies have examined insomnia in veterans with military sexual trauma (MST). We assess prevalence of insomnia, identify types of services sought by veterans with insomnia, and examine correlates of insomnia in veterans with and without MST., Design: A cross-sectional study of first-encounter veterans registering to establish care., Setting: Veteran Affairs San Diego Healthcare System., Participants: Nine hundred seventeen veterans completed questionnaires assessing insomnia, MST, service needs, traumatic brain injury, resilience, and symptoms of depression, posttraumatic stress disorder (PTSD), pain, alcohol misuse, and hypomania., Interventions: N/A., Measurements and Results: 53.1% of veterans without MST and 60.8% of veterans with MST had clinically significant insomnia symptoms, with the MST subsample reporting more severe symptoms, P < 0.05. Insomnia was more prevalent than depression, hypomania, PTSD, and substance misuse. Veterans with insomnia were more likely to seek care for physical health problems and primary care versus mental health concerns, P < 0.001. For the veteran sample without MST, age, combat service, traumatic brain injury, pain, and depression were associated with worse insomnia, P < 0.001. For the MST subsample, employment status, pain, and depression were associated with worse insomnia, P < 0.001., Conclusions: Study findings indicate a higher rate of insomnia in veterans compared to what has been found in the general population. Insomnia is more prevalent, and more severe, in veterans with military sexual trauma. Routine insomnia assessments and referrals to providers who can provide evidence-based treatment are crucial., (© 2015 Associated Professional Sleep Societies, LLC.)

Little is known about sleep in elite military populations who are exposed to higher operational demands, unpredictable training, deployment, and mission cycles. Twenty-nine Naval Special Warfare (NSW) Operators wore an actiwatch for an 8-day/7-night period for objective sleep assessment and completed a nightly sleep log. A total of 170 nights of actigraphically recorded sleep were collected. When comparing objectively versus subjectively recorded sleep parameter data, statistically significant differences were found. Compared with sleep log data, actigraphy data indicate NSW Operators took longer to fall asleep (an average of 25.82 minutes), spent more time awake after sleep onset (an average of 39.55 minutes), and demonstrated poorer sleep efficiency (83.88%) (ps < 0.05). Self-reported sleep quality during the study period was 6.47 (maximum score = 10). No relationships existed between the objectively derived sleep indices and the self-reported measure of sleep quality (rs = -0.29 to 0.09, all ps > 0.05). Strong inter-relationships existed among the subjectively derived sleep indices (e.g., between self-reported sleep quality and sleep efficiency; r = 0.61, p < 0.001). To our knowledge, this is the first study to objectively and subjectively quantify sleep among NSW Operators. These findings suggest sleep maintenance and sleep efficiency are impaired when compared to normative population data., (Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.)

Purpose of the Research: There is increasing interest in including measures of biological mechanisms as mediators and moderators of treatment outcome in randomized controlled trials (RCT's) of psychotherapy efficacy. However, examining biological mechanisms is often expensive and budget caps of most major funding agencies have remained stable in recent years. The goal of this manuscript is to describe how a psychotherapy efficacy trial is using a model of collaborative, affiliated grants to maximize resources and the potential knowledge to be gained from a single site RCT. Principal results and conclusions: The trial is an ongoing RCT comparing two psychotherapies for the treatment of concurrent posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) with a sample of treatment seeking veterans. Through collaboration with a team of investigators with independently-funded but affiliated grants, measures of select sleep, neurobiological, and genetic biomarkers were integrated into this single site RCT. This model has allowed us to pose research questions regarding the role of biological mechanisms, maximize the utility of recruitment, and be efficient in maximizing knowledge to be gained in a way that would not be possible solely on the funding of a single site RCT. Challenges of this model include high participant burden in regard to assessment and complicated coordinating procedures among studies. Strategies to address these challenges are described., (Published by Elsevier Inc.)

Objectives: This study examined: (a) the relationship between self-reported posttraumatic stress disorder (PTSD) symptoms and risk of obstructive sleep apnea (OSA) in a younger, Iraq and Afghanistan (OEF/OIF/OND) veteran sample seeking treatment for PTSD; and (b) the relationships between PTSD symptom scores and each risk factor of OSA (snoring, fatigue, high blood pressure/BMI)., Methods: Participants were 195 Iraq and Afghanistan veterans presenting to a VA outpatient PTSD clinic for evaluation. Veterans were 21 to 59 years old (mean 33.40, SD 8.35) and 93.3% male (n = 182). Logistic regressions were run to examine whether veterans with greater PTSD symptom severity had an increased probability of screening as high risk for OSA, even after controlling for known risk factors (older age, positive smoking status, and use of CNS depressants)., Results: Of 159 veterans screened, 69.2% were assessed as being at high risk for OSA. PTSD symptom severity increased the risk of screening positive for OSA. PTSD symptom severity increased risk of screening positive for snoring and fatigue, but not high blood pressure/BMI., Conclusions: OEF/OIF/OND veterans with PTSD screen as high risk for OSA at much higher rates than those seen in community studies and may not show all classic predictors of OSA (i.e., older and higher BMI). This study is the first to suggest that the Berlin may be a useful screener for OSA in a younger OEF/OIF/OND veteran population with PTSD. Screening of younger veterans with PTSD for OSA should be standard care, and polysomnography and OSA interventions should be readily available to younger veterans., (© 2015 American Academy of Sleep Medicine.)

Sleep disturbances are prevalent in posttraumatic stress disorder (PTSD) and are associated with a number of adverse health consequences. Few studies have used comprehensive assessment methods to characterize sleep in Operation Iraqi Freedom/Operation Enduring Freedom/Operation New Dawn (OEF/OIF/OND) veterans with PTSD. OEF/OIF/OND veterans with PTSD and sleep disturbance (n = 45) were compared to patients with primary insomnia (n = 25) and healthy control subjects (n = 27). Participants were assessed using questionnaire-based measures as well as daily subjective and objective measures of sleep. The 3 groups were compared with regard to (a) group means, (b) intraindividual (i.e., night-to-night) variability of sleep, and (c) interindividual (i.e., within-group) variability of sleep. In terms of group means, only objective sleep efficiency was significantly worse with PTSD than with primary insomnia (d = 0.54). Those with PTSD differed from those with primary insomnia on measures of intraindividual as well as interindividual variability (d = 0.48-0.73). These results suggested sleep symptoms in OEF/OIF/OND veterans with PTSD are more variable across nights and less consistent across patients relative to sleep symptoms in insomnia patients without PTSD. These findings have implications for research, as well as for personalizing treatment for individuals with PTSD., (Published 2015. This article is a US Government work and is in the public domain in the USA.)

Few studies have examined the effects of total sleep deprivation (TSD) on cognitive performance and brain activation using functional MRI (fMRI) in older adults. The current study examines blood oxygen level-dependent (BOLD) activation in older adults and younger adults during the sustained attention (GO) and response inhibition (NOGO) portions of a GO-NOGO cognitive task following 36 hr of total sleep deprivation. No significant performance differences were observed between the groups on the behavioral outcome measures of total hits and false alarms. Neuroimaging results, however, revealed a significant interaction between age-group and sleep-deprivation status. Specifically, older adults showed greater BOLD activation as compared to younger adults after 36 hours total sleep deprivation in brain regions typically associated with attention and inhibitory processes. These results suggest in order for older adults to perform the GO-NOGO task effectively after sleep deprivation, they rely on compensatory recruitment of brain regions that aide in the maintenance of cognitive performance.

We aimed to identify brain functional correlates of working memory performance in aging, in hopes of facilitating understanding of mechanisms that promote better versus worse working memory in late-life. Among 64 healthy adults, aged 23 to 78, we examined the relationship between age, working memory performance, and brain functional response during task performance. We focused on the association between working memory load-modulated functional response and individual differences in performance and whether these function-performance relationships differed with age. As expected, older age was associated with poorer working memory performance. Older age was also associated with reduced load-modulated activation including in bilateral prefrontal and parietal regions and left caudate as well as reduced deactivation including in the medial prefrontal cortex. Contrary to findings of hyperactivation in aging, we found no evidence of increased activation with older age. Positive associations identified between brain response and performance did not differ with age. Our findings suggest that the neural mechanisms underlying better versus worse working memory performance are age-invariant across adulthood, and argue against a pattern of functional reorganization in aging. Results are discussed within the broader literature, in which significant heterogeneity in findings between studies has been common.

Fear conditioning is considered an animal model of post-traumatic stress disorder. Such models have shown fear conditioning disrupts subsequent rapid eye movement sleep (REM). Here, we provide a translation of these models into humans. Using the fear potentiated startle (FPS) procedure, we examined the effects of fear conditioning and safety signal learning on subsequent REM sleep in healthy adults. We also examined the effects of changes in REM sleep on retention of fear and safety learning. Participants (n = 42 normal controls) spent 3 consecutive nights in the laboratory. The first was an adaptation night. Following the second night, we administered a FPS procedure that included pairing a wrist shock with a threat signal and a safety signal never paired with a shock. The next day, we administered the FPS procedure again, with no wrist shocks to any stimulus, to measure retention of fear and safety. Canonical correlations assessed the relationship between FPS response and REM sleep. Results demonstrated that increased safety signal learning during the initial acquisition phase was associated with increased REM sleep consolidation that night, with 28.4% of the variance in increased REM sleep consolidation from baseline accounted for by safety signal learning. Overnight REM sleep was, in turn, related to overnight retention of fear and safety learning, with 22.5% of the variance in startle retention accounted for by REM sleep. These data suggest that sleep difficulties, specifically REM sleep fragmentation, may play a mechanistic role in post-traumatic stress disorder via an influence on safety signal learning and/or threat-safety discrimination., (Copyright © 2014 the authors 0270-6474/14/3411754-07$15.00/0.)

Background: Working memory and underlying functional brain deficits have been observed in euthymic bipolar disorder (BD) patients, though there is heterogeneity in the degree of deficits. Sleep/circadian rhythm abnormalities are thought to be a core component of BD and may explain some of the heterogeneity in functional abnormalities. This preliminary study examined associations between sleep/circadian rhythm abnormalities and functional magnetic resonance imaging (fMRI) brain response on a working memory task among BD patients., Methods: Fourteen euthymic medicated BD patients wore an actigraph for 7 days before undergoing fMRI with a working memory task. Two matched healthy comparison (HC) groups were used (14 in each sample). One group completed the actigraphy portion and the other completed the fMRI portion of the study. Circadian activity rhythm and sleep variables were calculated and compared between BD and HC participants. Variables that significantly differed were used to examine the association between activity rhythms/sleep abnormalities and fMRI working memory brain response in anatomically defined regions., Results: Sleep efficiency and the rhythm robustness, mesor, and amplitude-to-width ratio were significantly abnormal in BD patients. Individual variability in all the sleep/circadian variables was significantly associated with the degree of abnormality of brain response in the dorsolateral prefrontal cortex and supramarginal gyri., Limitations: Small sample size and multiple comparison groups limit the interpretability of these findings., Conclusions: BD patients have abnormal activity rhythms and sleep efficiency, which are associated with abnormal working memory brain response. These preliminary findings support the notion that the sleep/circadian system is important in the functional brain deficits among BD patients., (Published by Elsevier B.V.)

Sleep disruption is an emergent military health issue, but remarkably little is known of its prevalence or comorbidities in the combat zone. This study was designed to quantify the prevalence and mental health correlates of sleep disruption among military personnel serving within a ground combat zone during Operation Enduring Freedom. This was a large, cross-sectional survey of active duty and reserve U.S. Navy personnel (N = 3,175). Self-reported sleep measures included total hours of sleep per day, total hours of sleep required to feel well-rested, difficulty falling asleep, and difficulty staying asleep. The survey also measured mental health symptoms, including post-traumatic stress symptoms, anxiety, and depression. Participants reported an average of 5.9 hours of sleep per day despite requiring on average 6.8 hours to feel well rested. More than half (56%) were classified as sleep deficient, and 67% reported 6 or fewer hours of sleep per day. Adjusted for covariates, individuals endorsing sleep disruption were at substantially elevated risk of meeting criteria for post-traumatic stress disorder, generalized anxiety disorder, and major depressive disorder. This study documents the prevalence of sleep disruption in a very large and difficult-to-access sample of military members serving in a combat zone, and details robust associations with mental health., (Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.)

Study Objective: To assess the effect of armodafinil on task-related prefrontal cortex activation using functional magnetic resonance imaging (fMRI) in patients with obstructive sleep apnea (OSA) and excessive sleepiness despite continuous positive airway pressure (CPAP) therapy., Methods: This 2-week, multicenter, prospective, randomized, double-blind, placebo-controlled, parallel-group study was conducted at five neuroimaging sites and four collaborating clinical study centers in the United States. Patients were 40 right-handed or ambidextrous men and women aged between 18 and 60 years, with OSA and persistent sleepiness, as determined by multiple sleep latency and Epworth Sleepiness Scale scores, despite effective, stable use of CPAP. Treatment was randomized (1:1) to once-daily armodafinil 200 mg or placebo. The primary efficacy outcome was a change from baseline at week 2 in the volume of activation meeting the predefined threshold in the dorsolateral prefrontal cortex during a 2-back working memory task. The key secondary measure was the change in task response latency., Results: No significant differences were observed between treatment groups in the primary or key secondary outcomes. Armodafinil was generally well tolerated. The most common adverse events (occurring in more than one patient [5%]) were headache (19%), nasopharyngitis (14%), and diarrhea (10%)., Conclusions: Armodafinil did not improve fMRI-measured functional brain activation in CPAP-treated patients with OSA and excessive sleepiness., Study Registration: Double-Blind, Placebo-Controlled, Functional Neuroimaging Study of Armodafinil (200 mg/Day) on Prefrontal Cortical Activation in Patients With Residual Excessive Sleepiness Associated With Obstructive Sleep Apnea/Hypopnea.

Study Objectives: To examine neural correlates of working memory performance in patients with primary insomnia (PIs) compared with well-matched good sleepers (GSs)., Design: Twenty-five PIs and 25 GSs underwent functional MRI while performing an N-back working memory task., Setting: VA hospital sleep laboratory and University-based functional imaging center., Patients or Participants: 25 PIs, 25 GSs., Interventions: N/A., Measurements and Results: Although PIs did not differ from GSs in cognitive performance, PIs showed the expected differences from GSs in both self-reported and objective sleep measures. PIs, relative to GSs, showed reduced activation of task-related working memory regions. This manifested both as an overall reduction in activation of task-related regions and specifically as reduced modulation of right dorsolateral prefrontal cortex with increasing task difficulty. Similarly, PIs showed reduced modulation (i.e., reduced deactivation) of default mode regions with increasing task difficulty, relative to GSs. However, PIs showed intact performance., Conclusions: These data establish a profile of abnormal neural function in primary insomnia, reflected both in reduced engagement of task-appropriate brain regions and an inability to modulate task-irrelevant (i.e., default mode) brain areas during working memory performance. These data have implications for better understanding the neuropathophysiology of the well established, yet little understood, discrepancy between ubiquitous subjective cognitive complaints in primary insomnia and the rarely found objective deficits during testing.

An important function of sleep is the consolidation of memories, and features of sleep, such as rapid eye movement (REM) or sleep spindles, have been shown to correlate with improvements in discrete memory domains. Because of the methodological difficulties in modulating sleep, however, a causal link between specific sleep features and human memory consolidation is lacking. Here, we experimentally manipulated specific sleep features during a daytime nap via direct pharmacological intervention. Using zolpidem (Ambien), a short-acting GABAA agonist hypnotic, we show increased sleep spindle density and decreased REM sleep compared with placebo and sodium oxybate (Xyrem). Naps with increased spindles produced significantly better verbal memory and significantly worse perceptual learning but did not affect motor learning. The experimental spindles were similar to control spindles in amplitude and frequency, suggesting that the experimental intervention enhanced normal sleep processes. Furthermore, using statistical methods, we demonstrate for the first time a critical role of spindles in human hippocampal memory performance. The gains in memory consolidation exceed sleep-alone or control conditions and demonstrate the potential for targeted, exceptional memory enhancement in healthy adults with pharmacologically modified sleep.

Objective: A fundamental dissociation for most working memory (WM) theories involves the separation of sensory-perceptual encoding of stimulus information from the maintenance of this information. The present paper reports tests of this separability hypothesis for visually presented pseudowords at both mathematical and neuroimaging levels of analysis., Method: Levels of analysis were linked by two experimental manipulations-visual degradation and pseudoword length variation-that coupled findings from a mathematical modeling study of WM performed in a separate sample to findings from an event-related functional MRI (fMRI) study reported in the present paper. Results from the mathematical modeling study generated parametric signatures of stimulus encoding and WM rehearsal and displacement. These signatures led to specific predictions about neurophysiological responses to study manipulations in a priori regions of interest (ROI)., Results: Results demonstrated predicted dissociations of activation signatures in several ROIs. Significant patterns of brain response mirroring the encode signature were observed only during the task encode interval and only in the visual cortex and posterior fusiform gyrus. In contrast, significant brain response mirroring the rehearsal/displacement signature was observed only in the dorsolateral prefrontal cortex, inferior frontal gyrus, and supramarginal gyrus., Conclusions: Present findings support the separability hypothesis insofar as brain regions that underlie sensory-perceptual processes demonstrated encode signatures whereas brain regions that support WM maintenance demonstrated the rehearsal/displacement signature. These results also provide evidence for the utility of combining mathematical modeling with fMRI to integrate information across cognitive and neural levels of analysis., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

Sleep loss affects attention by reducing levels of arousal and alertness. The neural mechanisms underlying the compensatory efforts of the brain to maintain attention and performance after sleep deprivation (SD) are not fully understood. Previous neuroimaging studies of SD have not been able to separate the effects of reduced arousal from the effects of SD on cerebral responses to cognitive challenges. Here, we used a simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) approach to study the effects of 36 h of total sleep deprivation (TSD). Specifically, we focused on changes in selective attention processes as induced by an active acoustic oddball task, with the ability to isolate runs with objective EEG signs of high (SD(alert)) or reduced (SD(sleepy)) vigilance. In the SD(alert) condition, oddball task-related activity appears to be sustained by compensatory co-activation of insular regions, but task-negative activity in the right posterior node of the default mode network is altered following TSD. In the SD(sleepy) condition, oddball task-positive activity was massively impaired, but task-negative activation was showing levels comparable with the control condition after a well-rested night. Our results suggest that loss of strict negative correlation between oddball task-positive and task-negative activation reflects the effects of TSD, while the actual state of vigilance during task performance can affects either task-related or task-negative activity, depending on the exact vigilance level.

Disrupted sleep is more common in older adults (OLD) than younger adults (YOUNG), often co-morbid with other conditions. How these sleep disturbances affect cognitive performance is an area of active study. We examined whether brain activation during verbal encoding correlates with sleep quantity and quality the night before testing in a group of healthy OLD and YOUNG. Twenty-seven OLD (ages 59-82) and 27 YOUNG (ages 19-36) underwent one night of standard polysomnography. Twelve hours post-awakening, subjects performed a verbal encoding task while undergoing functional magnetic resonance imaging. Analyses examined the group (OLD vs. YOUNG) by prior sleep quantity (total sleep time, TST) or quality (sleep efficiency, SE) interaction on cerebral activation, controlling for performance. Longer TST promoted higher levels of activation in the bilateral anterior parahippocampal in OLD and lower activation levels in the left anterior parahippocampus in YOUNG. Greater SE promoted higher activation levels in the left posterior parahippocampus and right inferior frontal gyrus in YOUNG, but not in OLD. The roles of these brain regions in verbal encoding suggest, in OLD, longer sleep duration may be linked to the ability to engage in functional compensation during cognitive challenges. By contrast, in YOUNG, shorter sleep duration may necessitate functional compensation to maintain cognitive performance, similar to what is seen following acute sleep deprivation. Additionally, in YOUNG, better sleep quality may improve semantic retrieval processes, thereby aiding encoding.

Emerging evidence supports the notion of disrupted sleep as a core component of Posttraumatic Stress Disorder (PTSD). Effective treatments for nighttime PTSD symptoms are critical because sleep disruption may be mechanistically linked to development and maintenance of PTSD and is associated with significant distress, functional impairment, and poor health. This review aimed to describe the state of science with respect to the impact of the latest behavioral and pharmacological interventions on posttraumatic nightmares and insomnia. Published studies that examined evidence for therapeutic effects upon sleep were included. Some behavioral and pharmacological interventions show promise, especially for nightmares, but there is a need for controlled trials that include valid sleep measures and are designed to identify treatment mechanisms. Our ability to treat PTSD-related sleep disturbances may be improved by moving away from considering sleep symptoms in isolation and instead conducting integrative studies that examine sequential or combined behavioral and/or pharmacological treatments targeting both the daytime and nighttime aspects of PTSD. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'., (Published by Elsevier Ltd.)

Sleep deprivation has adverse consequences for a variety of cognitive functions. The exact effects of sleep deprivation, though, are dependent upon the cognitive process examined. Within working memory, for example, some component processes are more vulnerable to sleep deprivation than others. Additionally, the differential impacts on cognition of different types of sleep deprivation have not been well studied. The aim of this study was to examine the effects of one night of total sleep deprivation and 4 nights of partial sleep deprivation (4 hours in bed/night) on two components of visual working memory: capacity and filtering efficiency. Forty-four healthy young adults were randomly assigned to one of the two sleep deprivation conditions. All participants were studied: 1) in a well-rested condition (following 6 nights of 9 hours in bed/night); and 2) following sleep deprivation, in a counter-balanced order. Visual working memory testing consisted of two related tasks. The first measured visual working memory capacity and the second measured the ability to ignore distractor stimuli in a visual scene (filtering efficiency). Results showed neither type of sleep deprivation reduced visual working memory capacity. Partial sleep deprivation also generally did not change filtering efficiency. Total sleep deprivation, on the other hand, did impair performance in the filtering task. These results suggest components of visual working memory are differentially vulnerable to the effects of sleep deprivation, and different types of sleep deprivation impact visual working memory to different degrees. Such findings have implications for operational settings where individuals may need to perform with inadequate sleep and whose jobs involve receiving an array of visual information and discriminating the relevant from the irrelevant prior to making decisions or taking actions (e.g., baggage screeners, air traffic controllers, military personnel, health care providers).

Dhh1 and Pat1 in yeast are mRNA decapping activators/translational repressors thought to play key roles in the transition of mRNAs from translation to degradation. However, little is known about the physical and functional relationships between these proteins and the translation machinery. We describe a previously unknown type of diauxic shift-dependent modulation of the intracellular locations of Dhh1 and Pat1. Like the formation of P bodies, this phenomenon changes the spatial relationship between components involved in translation and mRNA degradation. We report significant spatial separation of Dhh1 and Pat1 from ribosomes in exponentially growing cells. Moreover, biochemical analyses reveal that these proteins are excluded from polysomal complexes in exponentially growing cells, indicating that they may not be associated with active states of the translation machinery. In contrast, under diauxic growth shift conditions, Dhh1 and Pat1 are found to co-localize with polysomal complexes. This work suggests that Dhh1 and Pat1 functions are modulated by a re-localization mechanism that involves eIF4A. Pull-down experiments reveal that the intracellular binding partners of Dhh1 and Pat1 change as cells undergo the diauxic growth shift. This reveals a new dimension to the relationship between translation activity and interactions between mRNA, the translation machinery and decapping activator proteins.

This study aimed to determine if actigraphy could differentiate sleep and wake during a daytime nap and no-nap rest period. Fifty-seven subjects participated in the study; 30 subjects were in the nap group and the remaining 27 in the no-nap comparison group. All subjects wore actigraphs while simultaneously undergoing polysomnography (PSG). Three actigraphic sensitivity levels (high, medium, low) and two interval duration minimums (15 and 40 min) were used to score the nap and no-nap data. The variables examined included total sleep time (TST), sleep latency (SL), wake after sleep onset (WASO) and sleep efficiency (SE). The Bland-Altman technique was used to determine concordance. Epoch-by-epoch analysis examined actigraphic accuracy, sensitivity and specificity. For the naps, all actigraph settings except low-40 showed significant correlations with TST. The high and medium settings predicted SE significantly and the high settings predicted SL significantly. Bland-Altman analyses demonstrated high settings overestimated TST while high and medium settings overestimated SE. Overall, for the nap condition accuracy for the actigraph was 82-86%, sensitivity was 92-96% and specificity was 40-67%. In the no-nap condition, accuracy for the actigraph was 60-84%, sensitivity was 47-78% and specificity was 60-86%. Medium-40 and low-40 were the only settings that did not misidentify sleep in the no-nap condition. These results suggest that actigraphy can predict TST, SE and SL reliably, depending upon parameter settings, and actigraphy is a highly sensitive but not specific measure for daytime naps. Different actigraphy settings may be optimal depending upon the variables of interest. Discrimination of sleep and wake during periods of waking quiescence is not as robust as during periods of mainly daytime sleep., (© 2010 European Sleep Research Society.)

Imagery Rehearsal Therapy (IRT) has been shown to be efficacious in reducing nightmares, but the treatment has not been well-studied in veterans. The effectiveness of IRT was assessed from a chart review of veterans seeking outpatient treatment for chronic, trauma-related nightmares. Of those offered IRT, veterans who completed a full course of treatment for PTSD in the past year were more likely to initiate treatment. However, completion of IRT was not related to previous treatment, demographic variables, or nightmare severity reported at the first treatment session. Treatment completers reported significant reductions in nightmare frequency and intensity, severity of insomnia, and subjective daytime PTSD symptoms. Insomnia and PTSD symptoms, on average, were below clinical cutoffs following treatment, and 23% of patients showed a complete treatment response (< or =1 nightmare/week). Findings suggest IRT may be an effective short-term treatment for nighttime and daytime PTSD symptoms among veterans who complete a full course of treatment., (2009. Published by Elsevier Ltd.)

Conservation efforts at local, regional, and global scales often focus on threatened species despite recent calls to adopt more equitable and potentially more economically rational approaches. Critics contend that conservation planning centered only on threatened species fails to deliver cost-efficient conservation outcomes. We explored how planning to preserve threatened mammal species would influence the efficiency and effectiveness of conservation investments in East Kalimantan, Indonesia. We found that the explicit protection of threatened species delivered cost-efficient outcomes in this situation, afforded adequate protection to over 90% of those species not yet considered endangered, and contributed to the partial protection of the remainder. We used Marxan, a conservation planning tool, to determine the frequency that planning units are selected in efficient reserve systems and assessed the relative risk of deforestation of each planning unit. Our methods allowed us to identify areas of the region that require the most urgent conservation action.

This study examined sleep changes following cessation of marijuana and alcohol use during late adolescence. Twenty-nine heavy marijuana and alcohol users and 20 matched controls were studied during a 28-day monitored abstinence period. Sleep was examined as a function of prior substance use during Nights 1-2 and Nights 27-28. On Night 2, percent rapid eye movement sleep was predicted by past month alcohol use, whereas percent slow wave sleep was predicted by marijuana intake. By Night 28, neither alcohol nor marijuana use predicted any sleep architecture measure. However, on Night 28, indices of period limb movements (PLMs) in sleep were predicted by marijuana and alcohol intake. Results indicate that in adolescents: (1) cessation of heavy marijuana and alcohol use may influence sleep; (2) most sleep abnormalities abate within several weeks of abstinence; and (3) PLMs may increase following abstinence.

This study examined response inhibition during a Go-NoGo task in individuals with obstructive sleep apnea (OSA). Fourteen OSA patients and 14 controls were studied with functional magnetic resonance imaging. Compared to controls, the OSA group showed more false positives (error of commission) during the NoGo trials with decreased brain activation in the left postcentral gyrus, cingulate gyrus and inferior parietal lobe, as well as right insula and putamen. This is consistent with previous findings of impaired performance and decreased brain activation in OSA patients during a working memory task, suggesting that compromised brain function in response to cognitive challenges may underlie some of the cognitive deficits seen in patients with OSA.

Objective: To summarize the current literature regarding the significant prevalence and potential consequences of sleep disturbance following traumatic brain injury (TBI), particularly mild TBI., Design: PubMed and Ovid/MEDLINE databases were searched by using key words "sleep disturbance," "insomnia," "TBI," "brain injury," and "circadian rhythms." Additional sources (eg, abstracts from the annual Associated Professional Sleep Societies meeting) were also reviewed., Results: Sequelae of TBI include both medical and psychiatric symptoms and frequent complaints of sleep disturbance. Sleep disturbance likely result from and contribute to multiple factors associated with the injury, all of which complicate recovery and resolution of symptoms. Interestingly, research now seems to indicate that mild TBI may be more correlated with increased likelihood of sleep disturbance than are severe forms of TBI., Conclusions: Sleep disturbance is a common consequence of TBI, but much more research is required to elucidate the nature and extent of this relation. Research needs to focus on (1) uncovering the specific types, causes, and severity of TBI that most often lead to sleep problems; (2) the specific consequences of sleep disturbance in this population (eg, impaired physical or cognitive recovery); and (3) the most effective strategies for the treatment of sleep-wake abnormalities in this population.

Study Objectives: The objectives of this study were to (1) characterize cognitive and cerebral correlates of attention and response speed in patients with obstructive sleep apnea (OSA) and (2) assess the association of performance and brain activation with measures of OSA severity., Design: Patients with OSA and controls were compared on performance and brain activation during a sustained attention task. The association of reaction time and brain activation with apnea-hypopnea index, nocturnal hypoxia, and arousals was assessed., Setting: Functional magnetic resonance imaging was conducted while participants performed a Go-No-Go task. The 'Go' trials of the Go-No-Go task were used to index attention processing., Participants: Fourteen patients with OSA and 14 normal control subjects with equivalent age, body mass index, blood pressure, and education., Interventions: N/A., Measurements and Results: Patients with OSA showed decreased brain activation in cingulate, frontal, and parietal regions typically involved in attention tasks, compared with control subjects. Within the patients with OSA, increasing arousal index, but not desaturation index, was associated with slower mean reaction time and with decreased brain activation in areas involved in arousal and attention, response selection, motor response, and decision making. The apnea-hypopnea index, by itself, was not associated with changes in cerebral response., Conclusions: Patients with OSA showed decreased brain activation compared with control subjects during an attention task. The association of arousal index (but not hypoxia) with slow reaction times and brain activation suggests that alertness and reaction times show greater correlations with measures of sleep disruption than with measures of hypoxia.

Caffeine, the world's most common psychoactive substance, is used by approximately 90% of North Americans everyday. Little is known, however, about its benefits for memory. Napping has been shown to increase alertness and promote learning on some memory tasks. We directly compared caffeine (200mg) with napping (60-90min) and placebo on three distinct memory processes: declarative verbal memory, procedural motor skills, and perceptual learning. In the verbal task, recall and recognition for unassociated words were tested after a 7h retention period (with a between-session nap or drug intervention). A second, different, word list was administered post-intervention and memory was tested after a 20min retention period. The non-declarative tasks (finger tapping task (FTT) and texture discrimination task (TDT)) were trained before the intervention and then retested afterwards. Naps enhanced recall of words after a 7h and 20min retention interval relative to both caffeine and placebo. Caffeine significantly impaired motor learning compared to placebo and naps. Napping produced robust perceptual learning compared with placebo; however, naps and caffeine were not significantly different. These findings provide evidence of the limited benefits of caffeine for memory improvement compared with napping. We hypothesize that impairment from caffeine may be restricted to tasks that contain explicit information; whereas strictly implicit learning is less compromised.

Background: Physical fitness and physical conditioning have long been valued by the military for their roles in enhancing mission-specific performance and reducing risk of injury in the warfighter. It is not known whether physical fitness plays a causal role in attenuating acute military stress reactions or the evolution of post-traumatic stress disorder., Objective: The objective of this study was to determine whether physical fitness influences the impact of stressful events during military survival training in 31 men., Methods: Participants self-reported their most recent Physical Readiness Test scores and completed a trait anxiety measure before survival training. Participants also completed the Impact of Events Scale (IES) 24 hours after training., Results: Aerobic fitness was inversely associated with the total IES score (p < 0.01, adjusted R2 = 0.19). When adjusted for trait anxiety, this relationship was substantially attenuated and no longer significant (p = 0.11). Trait anxiety was inversely associated with aerobic fitness (p < 0.05) and positively related to IES (p < 0.001)., Conclusions: Physical fitness may buffer stress symptoms secondary to extreme military stress and its effects may be mediated via fitness-related attenuations in trait anxiety.

Learning new information requires practice. The degree of learning can be influenced by the amount of practice and whether subjects sleep between sessions. Over-practice, however, can lead to performance deterioration. The interaction between practice-dependent deterioration and sleep-dependent learning needs more study. We examine whether the amount of practice before sleep alters learning, and whether prior sleep protects against deterioration. Two groups (N = 33) were tested three times across two days on an orientation discrimination task. The High practice group was tested twice before a night of sleep and once after, at 9 a.m., 7 p.m., and 9 a.m. The Low practice group was tested once before a night of sleep and twice after, at 7 p.m., 9 a.m., and 7 p.m. Overall, both groups showed (1) deterioration with repeated, within-day testing, (2) performance improvement only after a night of sleep, (3) similar amounts of sleep-dependent learning and practice-dependent deterioration. In summary, we found that sleep resets visual contrast thresholds to a lower baseline (i.e., produces learning), but does not prevent over-practice deterioration effects. Likewise, over-practice deterioration does not influence the magnitude of overnight learning on this task.