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Fatigue represents a significant driving risk. One predictor of fatigue, and driving impairment, is prior sleep length. However, it is currently unknown how much sleep driver’s perceive as necessary to drive safety. This may be an important contributor to a driver’s decision about whether they are safe to drive. There is also evidence that reduced prior sleep leads to increased risk-taking. The aim of this study was to investigate community perceptions regarding sleep duration and fatigued driving, and to determine if sleep duration influences risk perception in relation to fatigued driving. 1081 participants completed a telephone survey addressing sleep history, fatigued driving, and risk perception. The majority of the sample (62.4 %) thought a minimum of 6–8 h sleep was necessary to drive safely, however a small percentage (5.6 %) felt that less was necessary or reported that they did not know. Women tended to report that individuals need more hours of sleep to drive safely. Younger age and male gender were both associated with an increased likelihood of reporting having driven despite feeling too tired, and male gender alone with being more likely to report falling asleep at the wheel. Reduced sleep duration in the prior 48 h was associated with reports of driving when too tired, and the perception that less sleep was required to drive safely. These findings imply that the Australian public may need guidance about sleep and safe driving, particularly in regards to the potential for sleep to influence risk propensity.

Anecdotally, people report disturbed sleep when ‘on-call’ and field data suggest that being on-call, even if ‘undisturbed’, may result in sleep disturbance. We investigated changes to sleep when expecting a loud, on-call alarm as compared to sleep when not expecting an alarm. Healthy males (n = 16) aged 24.6 ± 4.0 years took part in a simulated on-call scenario involving two conditions; Control and on-call. Prior to the Control sleep, participants were told that they would not be woken during the night, prior to the on-call sleep, participants were told to expect a loud alarm during the night, following which they were to complete 2 h of testing. Sleep was measured using a standard 5-channel polysomnograhic (PSG) montage. Sleep diaries were used to compare subjective variables; pre- and post-sleep sleepiness and sleep quality. There was no significant difference between the two nights for any of the PSG variables, except for REM where there was a non-significant trend (p = .051) with 8 min more REM on the on-call night. Participants were significantly sleepier following the on-call night, likely due to the earlier wake time (p

Study Objectives: To assess sleep inertia following 10-min and 30-min naps during a simulated night shift. Methods: Thirty-one healthy adults (aged 21–35 y; 18 females) participated in a 3-day laboratory study that included one baseline (BL) sleep (22:00–07:00)and one experimental night involving randomization to either: total sleep deprivation (NO-NAP), a 10-min nap (10-NAP) or a 30-min nap (30-NAP). Nap opportunities ended at 04:00. A 3-min psychomotor vigilance task (PVT-B), digit-symbol substitution task (DSST), fatigue scale, sleepiness scale, and self rated performance scale were undertaken pre-nap (03:00) and at 2, 17, 32, and 47 min post-nap. Results: The 30-NAP (14.7 ± 5.7 min) had more slow wave sleep than the 10-NAP (0.8 ± 1.5 min; P < 0.001) condition. In the NO-NAP condition, PVT-B performance was worse than pre-nap (4.6 ± 0.3 1/sec) at 47 min post-nap (4.1 ± 0.4 1/sec; P < 0.001). There was no change across time in the 10-NAP condition. In the 30-NAP condition, performance immediately deteriorated from pre-nap (4.3 ± 0.3 1/sec) and was still worse at 47 min post-nap (4.0 ± 0.51/sec; P < 0.015). DSST performance deteriorated in the NO-NAP (worse than pre-nap from 17 to 47 min; P < 0.008), did not change in the 10-NAP, and was impaired 2 min post-nap in the 30-NAP condition (P = 0.028). All conditions self-rated performance as better than pre-nap for all post-nap test points(P < 0.001). Conclusions: This study is the first to show that a 10-min (but not a 30-min) nighttime nap had minimal sleep inertia and helped to mitigate short-term performance impairment during a simulated night shift. Self-rated performance did not reflect objective performance following a nap. Refereed/Peer-reviewed

Study objectives To investigate the effects of sleep restriction (7 nights of 5 h time in bed [TIB]) on cognitive performance, subjective sleepiness, and mood in adolescents. Methods A parallel-group design was adopted in the Need for Sleep Study. Fifty-six healthy adolescents (25 males, age = 15-19 y) who studied in top high schools and were not habitual short sleepers were randomly assigned to Sleep Restriction (SR) or Control groups. Participants underwent a 2-w protocol consisting of 3 baseline nights (TIB = 9 h), 7 nights of sleep opportunity manipulation (TIB = 5 h for the SR and 9 h for the control groups), and 3 nights of recovery sleep (TIB = 9 h) at a boarding school. A cognitive test battery was administered three times each day. Results During the manipulation period, the SR group demonstrated incremental deterioration in sustained attention, working memory and executive function, increase in subjective sleepiness, and decrease in positive mood. Subjective sleepiness and sustained attention did not return to baseline levels even after 2 recovery nights. In contrast, the control group maintained baseline levels of cognitive performance, subjective sleepiness, and mood throughout the study. Incremental improvement in speed of processing, as a result of repeated testing and learning, was observed in the control group but was attenuated in the sleep-restricted participants, who, despite two recovery sleep episodes, continued to perform worse than the control participants. Conclusions A week of partial sleep deprivation impairs a wide range of cognitive functions, subjective alertness, and mood even in high-performing high school adolescents. Some measures do not recover fully even after 2 nights of recovery sleep. Commentary A commentary on this article appears in this issue on page 497.

Responding to an emergency alarm poses a significant risk to firefighters' health and safety, particularly to cardiovascular health, physical and psychological stress, and fatigue. These risks have been largely categorised for salaried firefighters working 'on station'. Less is known about the factors that contribute to these risks for the vast number of non-salaried personnel who serve in retained roles, often deploying from home. The present study investigated the alarm response procedure for Australian metropolitan fire fighters, identifying common and divergent sources of risk for salaried and retained staff. There were significant differences in procedure between the two workgroups and this resulted in differences in risk profile between groups. Sleep and fatigue, actual response to the alarm stimulus, work-life balance and trauma emerged as sources of risk experienced differently by salaried and retained firefighters. Key findings included reports of fatigue in both groups, but particularly in the case of retained firefighters who manage primary employment as well as their retained position. This also translated into a poor sense of work-life balance. Both groups reported light sleep, insufficient sleep or fragmented sleep as a result of alarm response. In the case of salaried firefighters, this was associated with being woken on station when other appliances are called. There were risks from physical and psychological responses to the alarm stimulus, and reports of sleep inertia when driving soon after waking. The findings of this study highlight the common and divergent risks for these workgroups, and could be used in the ongoing management of firefighters' health and safety.

Study Objective: This study sought to investigate the role of nocturnal sleep duration for the retrieval of oversleep consolidated memories, both prior to and after being cognitively stressed for similar to 30 minutes the next morning. Design: Participants learned object locations (declarative memory task comprising 15 card pairs) and a finger tapping sequence (procedural memory task comprising 5 digits) in the evening. After learning, participants either had a sleep opportunity of 8 hours (between similar to 23:00 and similar to 07:00, full sleep condition) or they could sleep between similar to 03:00 and similar to 07:00 (short sleep condition). Retrieval of both memory tasks was tested in the morning after each sleep condition, both before (similar to 08:30) and after being stressed (similar to 09:50). Setting: Sleep laboratory. Participants: 15 healthy young men. Results: The analyses demonstrated that oversleep memory changes did not differ between sleep conditions. However, in their short sleep condition, following stress hallmarked by increased subjective stress feelings, the men were unable to maintain their pre-stress performance on the declarative memory task, whereas their performance on the procedural memory task remained unchanged. While men felt comparably subjectively stressed by the stress intervention, overall no differences between pre- and post-stress recalls were observed following a full night of sleep. Conclusions: The findings suggest that 8-h sleep duration, within the range recommended by the US National Sleep Foundation, may not only help consolidate newly learned procedural and declarative memories, but also ensure full access to both during periods of subjective stress.

Sleep inertia, the state of reduced alertness upon waking, can negatively impact on-call workers. Anticipation of a stressful task on sleep inertia, while on-call was investigated. Young, healthy males (n = 23) spent an adaptation, control and two counterbalanced on-call nights in the laboratory. When on-call, participants were told they would be woken to a high or low stress task. Participants were not woken during the night, instead were given a 2300-0700 sleep opportunity. Participants slept ∼7.5-h in all conditions. Upon waking, sleep inertia was quantified using the Karolinska Sleepiness Scale and Psychomotor Vigilance and Spatial Configuration Tasks, administered at 15-min intervals. Compared to control, participants felt sleepier post waking when on-call and sleepiest in the low stress compared to the high stress condition (p .001). Spatial performance was faster when on-call compared to control (p .001). Findings suggest that anticipating a high-stress task when on-call, does not impact sleep inertia severity.

Time-of-day modulations affect both performance on a wide range of cognitive tasks and electrical activity of the brain, as recorded by electroencephalography (EEG). The aim of this work was to identify fluctuations of fractal properties of EEG time series due to circadian rhythms. In twenty-one healthy volunteers (all males, age between 20 and 30 years, chronotype: neutral type) high density EEG recordings at rest in open and closed eyes conditions were acquired in 4 times of the day (8.00 a.m., 11.30 a.m., 2.30 p.m., 7.00 p.m.). A vigilance task (Psychomotor Vigilance Test, PVT) was also performed. Detrended fluctuation Analysis (DFA) of envelope of alpha, beta and theta rhythms was performed, as well as Highuchi fractal dimension (HFD) of the whole band EEG. Our results evidenced circadian fluctuations of fractal features of EEG at rest in both eyes closed and eyes open conditions. Lower values of DFA exponent were found in the time T1 in closed eyes condition, likely effect of the sleep inertia. An alpha DFA exponent reduction was found also in central sensory-motor areas at time T3, the day time in which the sleepiness can be present. In eyes open condition, HFD lowered during the day. In eyes closed condition, an HFD increase was observed in central and frontal regions at time T2, the time in which alertness reaches its maximum and homeostatic sleep pressure is low. Complexity and the persistence of temporal correlations of brain rhythms change during daytime, parallel to changes in alertness and performance.

OBJECTIVES: Exposure to light can have acute alerting and circadian phase-shifting effects. This study investigated the effects of evening exposure to blue-enriched polychromatic white (BEL) vs. polychromatic white light (WL) on sleep inertia dissipation the following morning in older adults. METHODS: Ten healthy older adults (average age = 63.3 yrs; 6F) participated in a 13-day study comprising three baseline days, an initial circadian phase assessment, four days with 2-h evening light exposures, a post light exposure circadian phase assessment and three recovery days. Participants were randomized to either BEL or WL of the same irradiance for the four evening light exposures. On the next mornings at 2, 12, 22 and 32 minutes after each wake time, the participants completed a 90-s digit-symbol substitution test (DSST) to assess working memory, and objective alertness was assessed using a wake EEG recording. DSST and power density from the wake EEG recordings were compared between the two groups. RESULTS: DSST performance improved with time awake (p< 0.0001) and across study days in both light exposure groups (p< 0.0001). There was no main effect of group, although we observed a significant day × group interaction (p=0.0004), whereby participants exposed to BEL performed significantly better on the first two mornings after light exposures than participants in WL (post-hoc, p< 0.05). On those days, the BEL group showed higher EEG activity in some of the frequency bins in the sigma and beta range (p

Difficult early morning awakening is one of the defining symptoms of delayed sleep–wake phase disorder. It is accompanied by low cognitive arousal and drowsiness resulting in difficulty concentrating and focusing attention upon awakening. We designed the current study to quantitate cognitive performance (i.e. omissions, commissions, reaction time [average and variability]) and cognitive domains (i.e. focused attention, sustained attention, impulsivity and vigilance) with Conners’ Continuous Performance Test II during both habitual and conventional (00:00–07:00 hr) sleep–wake schedule in young adult patients with delayed sleep–wake phase disorder (n = 20, mean age = 24.8 years, SD = 3.0) and controls (n = 16, mean age = 24.4 years, SD = 3.4). Conners’ Continuous Performance Test II was administered after awakening and in the afternoon during both habitual and conventional conditions. In‐laboratory polysomnography was performed for 2 nights. We assessed sleep, tiredness, chronotype and depression using questionnaires. Saliva was sampled for dim light melatonin onset measurements. Repeated‐measures ANOVAs were applied for the Conners’ Continuous Performance Test II measures with group (patient/control), time (afternoon/morning) and condition (habitual/conventional schedule) as fixed factors. Patients with delayed sleep–wake phase disorder had reduced reaction times, especially in the morning, greater response speed variability, and made more omission and commission errors compared with controls. Patients with delayed sleep–wake phase disorder also had reduced focused attention, especially upon forced early awakening. The short total sleep time of patients with delayed sleep–wake phase disorder could not statistically explain this outcome. In conclusion, we observed a state‐dependent reduced ability to focus attention upon early morning awakening in patients with delayed sleep–wake phase disorder. Patients also had more omissions, longer reaction time and increased RT variability after habitual sleep, suggesting a possible small cognitive trait dysfunction in delayed sleep–wake phase disorder. This is the peer reviewed version of the following article:Cognitive performance in DSWPD patients upon awakening from habitual sleep compared with forced conventional sleep. Journal of Sleep Research 2018 s. 1-10, which has been published in final form at https://doi.org/10.1111/jsr.12730 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Human performances are reported to decrease during the period of sleep-to-wake transition, which is called sleep inertia. Lack of awareness of the performance impairment during this state may lead us to make mistakes, especially during driving. This study aims to investigate the difference in the electroencephalography (EEG) signals between alert and sleep inertia during eyes-closed condition based on fractal dimension and examine the differences between Fz, Cz, Pz, FCz and Oz. Nine healthy subjects had performed two sessions of the experiment; alert and sleep inertia. To obtain the sleep inertia state, subjects were needed to sleep in the provided room and the EEG signals were recorded and monitored by the researcher. Subjects were awakened from sleep after they reached the stage 3 of the first cycle of sleep for five minutes to reduce the inter-individual variation in the EEG signal. Each EEG signal were analyzed based on its fractal dimension estimated using Higuchi's algorithm. A kmax parameter of 80 has been selected for analyzing every 60 seconds of the signal with 512 Hz sampling rate. To support this analysis, a power spectrum of each signal was obtained and the correlation with the fractal dimension can be determined. The differences of fractal dimension and power spectrum between alert and sleep inertia state have been tested statistically using t-test. Fractal dimension estimated in sleep inertia EEG signal was higher than alert state and there were significant differences at Fz. Based on spectrum power, delta, theta and alpha power showed a significant difference at Fz and FCz. The significant difference of fractal dimension and delta, theta and alpha power found at Fz and FCz during eyes closed may be associated with the impairment of subject performances which related to the brain regions' functions.

International audience; Idiopathic hypersomnia (IH) is a poorly characterized orphan central disorder of hypersomnolence responsible for excessive daytime sleepiness (EDS), prolonged nighttime sleep and sleep inertia that often require long-term symptomatic stimulant medication. To date, no drug has currently the authorization for the treatment of IH patients worldwide. Areas covered: The authors reviewed data on pharmacological treatment of IH obtained from published literature (Medline/PubMed/Web of Science) and Clinicaltrial.gov database from 1997 to 2017. Most of data on treatment of IH derived from observational studies and case series with only three well-designed clinical trials available. Expert opinion: In two recent randomized, double-blind, placebo-controlled trials, modafinil improves EDS in IH. Most of other wakefulness-promoting agents labeled for narcolepsy have similar efficacy in cases series of IH patients. Pitolisant and sodium oxybate show promising results in two retrospective studies. The efficacy of γ-aminobutyric acid-A receptor antagonists on objective EDS needs to be clarified. All these medications are used off-label for the management of EDS in IH. Specific clinical instruments and objective tests are required in IH to better evaluate the severity of EDS and responsiveness to medications, but also prolonged sleep and sleep inertia, to optimize the whole management of IH patients.

There has been a vast development of personal informatics devices combining sleep monitoring with alarm systems, in order to find an optimal time to awaken a sleeping person in a pleasant way. Most of these systems implement auditory feedback as the alarm signal, which is not always pleasant and may disturb other sleepers in the same space. In this paper, we present an adaptive alarm system that detects sleeping cycles and triggers the alarm signal during shallow sleep, in order to minimize sleep inertia. Since tactile sensation is associated with positive valence, vibrotactile stimulation is investigated as a silent alarm to enhance pleasant awakening. Three modulation techniques to render the tactile stimuli for pleasant awakening are considered, namely simultaneous, continuous, and successive stimulation. Two experimental studied are conducted. Experiment 1 studied exogenous attention towards tactile stimulation in a multimodal scenario (involving visual and haptic interactions) with fully awake individuals. Results from the attention task and the subjective valence rating suggest that the vibrotactile stimulation should be based on the continuous modulation, since this not only is very perceivable but also associated with positive attention. Experiment 2 evaluated the user experience with tactile stimulation patterns during sleep. Results confirmed the findings of experiment 1. Continuous modulation was rated highest for pleasant yet arousing sleep-awake transition.

Objective Behavioral and physiological indexes of high sleep inertia (SI) characterize the awakening from recovery (REC) sleep after prolonged wakefulness, but the associated electroencephalogram (EEG) topography has never been investigated. Here, we compare the EEG topography following the awakening from baseline (BSL) and REC sleep. Methods We have recorded the EEG waking activity of 26 healthy subjects immediately after the awakening from BSL sleep and from REC sleep following 40 h of prolonged wakefulness. In both BSL and REC conditions, 12 subjects were awakened from stage 2 sleep, and 14 subjects from rapid eye movement (REM) sleep. The full-scalp waking EEG (eyes closed) was recorded after all awakenings. Results Subjects awakened from REC sleep showed a reduction of fronto-central alpha and beta-1 activities, while no significant effects of the sleep stage of awakening have been observed. Positive correlations between pre- and post-awakening EEG modifications following REC sleep have been found in the posterior and lateral cortices in the frequency ranges from theta to beta-2 and (only for REM awakenings) extending to the fronto-central regions in the beta-1 band, and in the midline central and parietal derivations for the alpha and delta bands, respectively. Conclusions These findings suggest that the higher SI after REC sleep may be due to the fronto-central decrease of alpha and beta-1 activity and to the persistence of the sleep EEG features after awakening in the posterior, lateral, and fronto-central cortices, without influences of the sleep stage of awakening.

Poor sleep quality has been demonstrated to diminish cognitive performance, impair psychosocial functioning and alter the perception of stress. At present, however, there is little understanding of how sleep quality affects emotion processing. The aim of the present study was to determine the extent to which sleep quality, measured through the Pittsburg Sleep Quality Index, influences affective symptoms as well as the interaction between stress and performance on an emotional memory test and sustained attention task. To that end, 154 undergraduate students (mean age: 21.27 years, standard deviation = 4.03) completed a series of measures, including the Pittsburg Sleep Quality Index, the Sustained Attention to Response Task, an emotion picture recognition task and affective symptom questionnaires following either a control or physical stress manipulation, the cold pressor test. As sleep quality and psychosocial functioning differ among chronotypes, we also included chronotype and time of day as variables of interest to ensure that the effects of sleep quality on the emotional and non-emotional tasks were not attributed to these related factors. We found that poor sleep quality is related to greater depressive symptoms, anxiety and mood disturbances. While an overall relationship between global Pittsburg Sleep Quality Index score and emotion and attention measures was not supported, poor sleep quality, as an independent component, was associated with better memory for negative stimuli and a deficit in sustained attention to non-emotional stimuli. Importantly, these effects were not sensitive to stress, chronotype or time of day. Combined, these results suggest that individuals with poor sleep quality show an increase in affective symptomatology as well as a negative cognitive bias with a concomitant decrease in sustained attention to non-emotional stimuli.

Summary Sleep inertia, sleep homeostatic and circadian processes modulate cognition, including reaction time, memory, mood and alertness. How these processes influence higher-order cognitive functions is not well known. Six participants completed a 73-day-long study that included two 14-day-long 28-h forced desynchrony protocols to examine separate and interacting influences of sleep inertia, sleep homeostasis and circadian phase on higher-order cognitive functions of inhibitory control and selective visual attention. Cognitive performance for most measures was impaired immediately after scheduled awakening and improved during the first ~2–4 h of wakefulness (decreasing sleep inertia); worsened thereafter until scheduled bedtime (increasing sleep homeostasis); and was worst at ~60° and best at ~240° (circadian modulation, with worst and best phases corresponding to ~09:00 and ~21:00 hours, respectively, in individuals with a habitual wake time of 07:00 hours). The relative influences of sleep inertia, sleep homeostasis and circadian phase depended on the specific higher-order cognitive function task examined. Inhibitory control appeared to be modulated most strongly by circadian phase, whereas selective visual attention for a spatial-configuration search task was modulated most strongly by sleep inertia. These findings demonstrate that some higher-order cognitive processes are differentially sensitive to different sleep–wake regulatory processes. Differential modulation of cognitive functions by different sleep–wake regulatory processes has important implications for understanding mechanisms contributing to performance impairments during adverse circadian phases, sleep deprivation and/or upon awakening from sleep.

Epidemiologic studies have shown that approximately 50% of older adults have sleep problems, many of which carry deleterious consequences that affect physical and mental health and also social functioning. However, sleep problems in late life are often unrecognized, and are inadequately treated in clinical practice. This article focuses on the diagnosis and treatment of the 2 most common sleep problems in older patients: sleep apnea and insomnia.

Objective: We aimed to build upon the state of knowledge about the impacts of sleep disruption into the domain of complex cognitive task performance for three types of sleep disruption: total sleep deprivation, sleep restriction, and circadian cycle. Background: Sleep disruption affects human performance by increasing the likelihood of errors or the time it takes to complete tasks, such as the Psychomotor Vigilance Task. It is not clear whether complex tasks are affected in the same way. Understanding the impact of sleep disruption on complex cognitive tasks is important for, and in some instances more relevant to, professional workers confronted with unexpected, catastrophic failures following a period of disrupted sleep. Method: Meta-analytic review methods were applied to each of the three different areas of sleep disruption research. Results: Complex cognitive task performance declines over consecutive hours of continuous wakefulness as well as consecutive days of restricted sleep, is worse for severely restricted sleep (4 or fewer hours in bed), is worse during the circadian nadir than apex, and appears less degraded than simple task performance. Conclusion: The reviews suggest that complex cognitive task performance may not be impacted by disrupted sleep as severely as simple cognitive task performance. Application: Findings apply to predicting effects of sleep disruption on workers in safety-critical environments, such as health care, aviation, the military, process control, and in particular, safety-critical environments involving shiftwork or long-duration missions.

Sleep Research Sleep deprivation, such as that experienced because of shift work, jet lag, sleep disorders, and aging, leads to deterioration of many aspects of health. Cognition deteriorates rapidly and substantially when we stay awake through the night. To investigate the time course of brain responses during sleep loss, Muto et al. scanned volunteers repeatedly during an extended period of wakefulness (see the Perspective by Czeisler) in which circadian and homeostatic drives differentially affected local brain regions. Science , this issue p. [687][1]; see also p. [648][2] [1]: /lookup/doi/10.1126/science.aad2993 [2]: /lookup/doi/10.1126/science.aah5402

Extended nap opportunities have been effective in maintaining alertness in the context of extended night shifts (+12 h). However, there is limited evidence of their efficacy during 8-h shifts. Thus, this study explored the effects of extended naps on cognitive, physiological and perceptual responses during four simulated, 8-h night shifts. In a laboratory setting, 32 participants were allocated to one of three conditions. All participants completed four consecutive, 8-h night shifts, with the arrangements differing by condition. The fixed night condition worked from 22h00 to 06h00, while the nap early group worked from 20h00 to 08h00 and napped between 00h00 and 03h20. The nap late group worked from 00h00 to 12h00 and napped between 04h00 and 07h20. Nap length was limited to 3 hours and 20 minutes. Participants performed a simple beading task during each shift, while also completing six to eight test batteries roughly every 2 h. During each shift, six test batteries were completed, in which the following measures were taken. Performance indicators included beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. Physiological measures included heart rate and tympanic temperature, whereas subjective sleepiness and reported sleep length and quality while outside the laboratory constituted the self reported measures. Both naps reduced subjective sleepiness but did not alter the circadian and homeostatic-related changes in cognitive and physiological measures, relative to the fixed night condition. Additionally, there was evidence of sleep inertia following each nap, which resulted in transient reductions in certain perceptual cognitive performance measures. The present study suggested that there were some benefits associated with including an extended nap during 8-h night shifts. However, the effects of sleep inertia need to be effectively managed to ensure that post-nap alertness and performance is maintained.

Sleepiness has repeatedly been demonstrated to affect performance on a variety of cognitive tasks. While the effects of total sleep deprivation have been extensively studied, acute partial sleep deprivation, a much more frequent form of sleep loss, has been studied much less often. The present study examined the effects of sleep deprivation on novel tasks involving classic sensory, working, and permanent memory systems. While the tasks did involve different memory systems, they shared a need for effortful, sustained attention to maintain successful performance. Because of the novelty of the tasks, an initial study of the effects of total sleep deprivation was carried out. The effects of partial sleep deprivation were subsequently examined in a second study, in which subjects were permitted only 4 hours of sleep. A general detrimental effect of both total and partial sleep deprivation on accuracy of detection was observed and to a lesser extent, a slowing of the speed of responding on the different tasks. This overall effect is best explained by the often-observed inability to sustain attention following sleep loss. Specific effects on distinct cognitive processes were also observed, and these were more apparent following total than partial sleep deprivation.

Older adults do not sleep as well as younger adults. Why? What alterations in sleep quantity and quality occur as we age, and are there functional consequences? What are the underlying neural mechanisms that explain age-related sleep disruption? This review tackles these questions. First, we describe canonical changes in human sleep quantity and quality in cognitively normal older adults. Second, we explore the underlying neurobiological mechanisms that may account for these human sleep alterations. Third, we consider the functional consequences of age-related sleep disruption, focusing on memory impairment as an exemplar. We conclude with a discussion of a still-debated question: do older adults simply need less sleep, or rather, are they unable to generate the sleep that they still need?

Study Objectives Fatigue from sleep loss is a risk to physician and patient safety, but objective data on physician sleep and alertness on different duty hour schedules is scarce. This study objectively quantified differences in sleep duration and alertness between medical interns working extended overnight shifts and residents not or rarely working extended overnight shifts. Methods Sleep-wake activity of 137 interns and 87 PGY-2/3 residents on 2-week Internal Medicine and Oncology rotations was assessed with wrist-actigraphy. Alertness was assessed daily with a brief Psychomotor Vigilance Test (PVT) and the Karolinska Sleepiness Scale. Results Interns averaged 6.93 hours (95% confidence interval [CI] 6.84-7.03 hours) sleep per 24 hours across shifts, significantly less than residents not working overnight shifts (7.18 hours, 95% CI 7.06-7.30 hours, p = .007). Interns obtained on average 2.19 hours (95% CI 2.02-2.36 hours) sleep during on-call nights (17.5% obtained no sleep). Alertness was significantly lower on mornings after on-call nights compared to regular shifts (p < .001). Naps between 9 am and 6 pm on the first day post-call were frequent (90.8%) and averaged 2.84 hours (95% CI 2.69-3.00 hours), but interns still slept 1.66 hours less per 24 hours (95% CI 1.56-1.76 hours) compared to regular shift days (p < .001). Sleep inertia significantly affected alertness in the 60 minutes after waking on-call. Conclusions Extended overnight shifts increase the likelihood of chronic sleep restriction in interns. Reduced levels of alertness after on-call nights need to be mitigated. A systematic comparison of sleep, alertness, and safety outcomes under current and past duty hour rules is encouraged.

Human cognitive performance is critical to productivity, learning, and accident avoidance. Cognitive performance varies throughout each day and is in part driven by intrinsic, near 24-hour circadian rhythms. Prior research on the impact of sleep and circadian rhythms on cognitive performance has typically been restricted to small-scale laboratory-based studies that do not capture the variability of real-world conditions, such as environmental factors, motivation, and sleep patterns in real-world settings. Given these limitations, leading sleep researchers have called for larger in situ monitoring of sleep and performance. We present the largest study to date on the impact of objectively measured real-world sleep on performance enabled through a reframing of everyday interactions with a web search engine as a series of performance tasks. Our analysis includes 3 million nights of sleep and 75 million interaction tasks. We measure cognitive performance through the speed of keystroke and click interactions on a web search engine and correlate them to wearable device-defined sleep measures over time. We demonstrate that real-world performance varies throughout the day and is influenced by both circadian rhythms, chronotype (morning/evening preference), and prior sleep duration and timing. We develop a statistical model that operationalizes a large body of work on sleep and performance and demonstrates that our estimates of circadian rhythms, homeostatic sleep drive, and sleep inertia align with expectations from laboratory-based sleep studies. Further, we quantify the impact of insufficient sleep on real-world performance and show that two consecutive nights with less than six hours of sleep are associated with decreases in performance which last for a period of six days. This work demonstrates the feasibility of using online interactions for large-scale physiological sensing., Comment: Published in Proceedings of WWW 2017

In recent years sleep-related memory consolidation has become a central topic in the sleep research field. Several studies have shown that in healthy individuals sleep promotes memory consolidation. Notwithstanding this, the consequences of sleep disorders on offline memory consolidation remain poorly investigated. Research studies indicate that patients with insomnia, obstructive sleep apnea, and narcolepsy often exhibit sleep-related impairment in the consolidation of declarative and procedural information. On the other hand, patients with parasomnias, such as sleep-walking, night terrors and rapid eye movement (REM) behavior disorder, do not present any memory impairment. These studies suggest that only sleep disorders characterized by increased post-learning arousal and disrupted sleep architecture seem to be associated with offline memory consolidation issues. Such impairments, arising already in childhood, may potentially affect the development and maintenance of an individual's cognitive abilities, reducing their quality of life and increasing the risk of accidents. However, promising findings suggest that successfully treating sleep symptoms can result in the restoration of memory functions and marked reduction of direct and indirect societal costs of sleep disorders.

International audience; Sleepiness is one of the most frequently reported complaints in adults and children during specialised sleep consultations. It is responsible for an alteration that can be severe in quality of life, a lowering of academic or professional performance, and domestic or work accidents. Hypersomnolence is the first cause of road accidents on the highway, responsible for a third of fatal accidents. Furthermore its presence is associated with an increased risk of morbi-mortality related to cardiovascular and neurodegenerative pathologies. Hence, its represents a real public health issue. Recent revisions in international classifications have clarified confusing terminology, and the complaint of hypersomnia has now been replaced by the terms hypersomnolence or excessive sleepiness. It is clinically defined as an excessive quantity of sleep over 24hours, and/or by an alteration in the quality of arousal defined as incapacity to maintain a satisfactory level of vigilance during the day or in the morning on awakening (defined as sleep inertia). The evaluation of sleepiness requires a rigorous clinical approach, completed by subjective and objective measurements. The Epworth Sleep Scale, Multiple Sleep Latency Tests and the Maintenance of Wakefulness Test are the most studied and used in clinical practice. However, to date, no gold standard measurement of excessive sleepiness exists, and there are no quantifiable biological markers. It is therefore important to optimise our evaluation tools, improve our pathophysiological understanding of sleepiness, and define genetic and environmental risk factors.

The recognition that sleep is one of the foundations of athlete performance is increasing both in the elite athlete arena as well as applied performance research. Sleep, as identified through sleep deprivation and sleep extension investigations, has a role in performance, illness, injury, metabolism, cognition, memory, learning, and mood. Elite athletes have been identified as having poorer quality and quantity of sleep in comparison to the general population. This is likely the result on training times, competition stress/anxiety, muscle soreness, caffeine use, and travel. Sleep, in particular slow wave sleep, provides a restorative function to the body to recover from prior wakefulness and fatigue by repairing processes and restoring energy. In addition, research in the general population is highlighting the importance of sleep on neurophysiology, cognitive function, and mood which may have implications for elite athlete performance. It is thus increased understanding of both the effects of sleep deprivation and potential mechanisms of influence on performance that may allow scientists and practitioners to positively influence sleep in athletes and ultimately maximize performances.

There are several influences on sleep during middle age, including natural reductions in sleep quantity, quality, efficiency, and ability. Chronic medical and psychiatric disorders may disrupt sleep. Several sleep disorders are very common during middle age, including obstructive sleep apnea and restless legs syndrome. Family, work, and financial responsibilities may lead to neglect of good sleep and health habits. Menopause is associated with greater sleep difficulty in women due to several reasons. Educating the middle-aged population about sleep disorders, sleep and lifestyle habits, and the effects of all of these on sleep quality, quality of life, and health is essential.

Sleep deprivation is associated with neurobehavioral deficits that include impairments in cognitive and psychomotor functions and alterations of mood. These effects appear to be due to instability of waking neurobiology resulting from sleep initiating systems when sleep drive is elevated. Attention, working memory, and divergent higher cognitive functions are particularly vulnerable to both total sleep deprivation and chronic partial sleep restriction. Few countermeasures to the neurobehavioral effects of sleep deprivation have been identified, and there is no substitute for sleep when it comes to stable wakefulness. Sleep duration is the best predictor of daily recovery of neurobehavioral functioning.

This study sought to determine if there is any overlap between the two major non-rapid eye movement and rapid eye movement parasomnias, i.e. sleepwalking/sleep terrors and rapid eye movement sleep behaviour disorder. We assessed adult patients with sleepwalking/sleep terrors using rapid eye movement sleep behaviour disorder screening questionnaires and determined if they had enhanced muscle tone during rapid eye movement sleep. Conversely, we assessed rapid eye movement sleep behaviour disorder patients using the Paris Arousal Disorders Severity Scale and determined if they had more N3 awakenings. The 251 participants included 64 patients with rapid eye movement sleep behaviour disorder (29 with idiopathic rapid eye movement sleep behaviour disorder and 35 with rapid eye movement sleep behaviour disorder associated with Parkinson's disease), 62 patients with sleepwalking/sleep terrors, 66 old healthy controls (age-matched with the rapid eye movement sleep behaviour disorder group) and 59 young healthy controls (age-matched with the sleepwalking/sleep terrors group). They completed the rapid eye movement sleep behaviour disorder screening questionnaire, rapid eye movement sleep behaviour disorder single question and Paris Arousal Disorders Severity Scale. In addition, all the participants underwent a video-polysomnography. The sleepwalking/sleep terrors patients scored positive on rapid eye movement sleep behaviour disorder scales and had a higher percentage of 'any' phasic rapid eye movement sleep without atonia when compared with controls; however, these patients did not have higher tonic rapid eye movement sleep without atonia or complex behaviours during rapid eye movement sleep. Patients with rapid eye movement sleep behaviour disorder had moderately elevated scores on the Paris Arousal Disorders Severity Scale but did not exhibit more N3 arousals (suggestive of non-rapid eye movement parasomnia) than the control group. These results indicate that dream-enacting behaviours (assessed by rapid eye movement sleep behaviour disorder screening questionnaires) are commonly reported by sleepwalking/sleep terrors patients, thus decreasing the questionnaire's specificity. Furthermore, sleepwalking/sleep terrors patients have excessive twitching during rapid eye movement sleep, which may result either from a higher dreaming activity in rapid eye movement sleep or from a more generalised non-rapid eye movement/rapid eye movement motor dyscontrol during sleep.

We describe performance models and meta-analytic data in a period before and after an unexpected workload transition typical, for example, of a catastrophic automation failure, experienced by a fatigued operator. We first present meta-analytic findings on the effects of sleep restriction and sleep inertia on the complex cognitive performance that might typify such a “failure response”. We then present a workload overload task management model whose parameters are based on meta-analyses, relevant to predicting multi-task performance in the post-transition phase performance (independent of sleep disruption effects). We cite the lack of research intersecting these two areas.

In children diagnosed with pediatric bipolar disorder (PBD), disturbances in the quality of sleep and wakefulness are prominent. A novel phenotype of PBD called Fear of Harm (FOH) associated with separation anxiety and aggressive obsessions is associated with sleep onset insomnia, parasomnias (nightmares, night-terrors, enuresis), REM sleep-related problems, and morning sleep inertia. Children with FOH often experience thermal discomfort (e.g., feeling hot, excessive sweating) in neutral ambient temperature conditions, as well as no discomfort during exposure to the extreme cold, and alternate noticeably between being excessively hot in the evening and cold in the morning. We hypothesized that these sleep- and temperature-related symptoms were overt symptoms of an impaired ability to dissipate heat, particularly in the evening hours near the time of sleep onset. We measured sleep/wake variables using actigraphy, and nocturnal skin temperature variables using thermal patches and a wireless device, and compared these data between children with PBD/FOH and a control sample of healthy children. The results are suggestive of a thermoregulatory dysfunction that is associated with sleep onset difficulties. Further, they are consistent with our hypothesis that alterations in neural circuitry common to thermoregulation and emotion regulation underlie affective and behavioral symptoms of the FOH phenotype.

Purpose: Young adults regularly experience restricted sleep due to a range of social, educational and vocational commitments. Evidence suggests that extended periods of sleep deprivation negatively impact affective and inhibitory control mechanisms leading to behavioural consequences such as increased emotional reactivity and impulsive behaviour. It is less clear whether acute periods of restricted sleep produce the same behavioural consequences. Methods: Nineteen young adults (m = 8, f = 12) with habitual late bed-time (after 22:30 h) and wake-time (after 06:30 h) completed a range of objective and subjective measures assessing sleepiness (Psychomotor Vigilance Task, Karolinska Sleepiness Scale), inhibitory control (Emotional Go/No-go Task and a Balloon Analog Risk Task) and affect (Positive and Negative Affective Schedule). Testing was counterbalanced across participants, and occurred on two occasions once following restricted sleep and once following habitual sleep one week apart. Results: Compared to habitual sleep, sleep restriction produced significantly slower performance on the Psychomotor Vigilance Task, and higher subjective ratings of sleepiness on the Karolinska Sleepiness Scale. Sleep restriction also caused a significant decrease in positive affect, but no change in negative affect on the Affective Schedule. Inhibitory control efficiency was significantly differentiated, with participants showing an increase in risk taking on the Balloon Analog Risk Task, but there was no evidence of increased reactivity to negative stimuli on the Emotional Go/No-go task. Conclusions: Results suggest that even acute periods of sleep loss may cause deficits in affective experiences and increase impulsive and potentially high risk behaviour in young adults.

Summary Successful memory consolidation during sleep depends on healthy slow-wave and rapid eye movement sleep, and on successful transition across sleep stages. In post-traumatic stress disorder, sleep is disrupted and memory is impaired, but relations between these two variables in the psychiatric condition remain unexplored. We examined whether disrupted sleep, and consequent disrupted memory consolidation, is a mechanism underlying declarative memory deficits in post-traumatic stress disorder. We recruited three matched groups of participants: post-traumatic stress disorder (n = 16); trauma-exposed non-post-traumatic stress disorder (n = 15); and healthy control (n = 14). They completed memory tasks before and after 8 h of sleep. We measured sleep variables using sleep-adapted electroencephalography. Post-traumatic stress disorder-diagnosed participants experienced significantly less sleep efficiency and rapid eye movement sleep percentage, and experienced more awakenings and wake percentage in the second half of the night than did participants in the other two groups. After sleep, post-traumatic stress disorder-diagnosed participants retained significantly less information on a declarative memory task than controls. Rapid eye movement percentage, wake percentage and sleep efficiency correlated with retention of information over the night. Furthermore, lower rapid eye movement percentage predicted poorer retention in post-traumatic stress disorder-diagnosed individuals. Our results suggest that declarative memory consolidation is disrupted during sleep in post-traumatic stress disorder. These data are consistent with theories suggesting that sleep benefits memory consolidation via predictable neurobiological mechanisms, and that rapid eye movement disruption is more than a symptom of post-traumatic stress disorder.

Aims: To quantify and model mathematically the effects on the subjectssleepwake cycle, alertness, and performance of the sleep phase shift due to working at times of the day when sleep propensity is high. Methodologi es: Thirty-seven police officers working on a fast counterclockwise schedule, filled for 25 consecutive days a self -administered questionnaire about the previous night sleep, subjective fatigue, sleep attacks, errors. For each subject, the hom eostatic process was computed according to the BorbEly -Achermann model. Night sleep decreased progressively during the shift schedule, with effects on sleep pressure Original ResearchArticle

Background: The notion of ‘functional uncertainty' during sleep was first proposed to indicate an inability of the central nervous system to maintain stable states by coordinating physiological processes. While the presence of functional uncertainty phenomena has been shown in infants and hypothesized in the elderly, its actual occurrence in the aged population has never been systematically investigated. Objective: The aim of the study is to identify, in the sleep of aged individuals, indexes of sleep instability and fragmentation as markers of functional uncertainty, by comparing a sample of healthy elderly subjects to one of young adults. Methods: We compared polysomnograhic recordings of 20 healthy elderly subjects (age range 65-85 years) with those of 20 young individuals (age range 22-32 years), with special regard to the variables expressing functional uncertainty in sleep, such as continuity (e.g. arousals, awakenings), stability (e.g. state transitions, periods of marked ‘functional uncertainty') and cyclic organization parameters. Results: Significant differences emerged for all variables of interest: the elderly group showed higher indexes of fragmentation and instability than the young, as well as less and shorter cycles, and a lower percentage of time spent in cycles. Conclusion: Our results support the hypothesis of a progressive sleep quality disruption with aging, expressed by pronounced sleep instability, fragmentation and disorganization. We propose that functional uncertainty measures could usefully be included in standard sleep assessments on both aged and sleep-disordered populations as accurate sleep quality indexes.