The comprehensive effect of sleep deprivation on biological and behavioral functions largely remains unknown. There is evidence to support that human sleep must be of sufficient duration and physiological continuity to ensure neurocognitive performance while we are waking. Insufficient sleep would lead to high risk of human-error related to accidents, injuries or even fatal outcomes. However, in modern society, more and more people suffer from sleep deprivation because of the increasing social, academic or occupational demand. It is important to study the effect of sleep deprivation, not only on task performance, but also on neurocognitive functions. Recent research that has explored brain effective connectivity has demonstrated the directed inference interaction among pairs of brain areas, which may bring important insight to understand how brain works to support neurocognitive function. This research aimed to identify the brain effective connectivity pattern associated with changes of a task performance, response time, following sleep deprivation. Experiments were conducted by colleagues at Neuroergonomics Department at Jagiellonian University, Krakow, Poland. Ten healthy young women, with an average age of 23-year-old, performed visual spatial sustained-attention tasks under two conditions: (1) the rest-wakeful (RW) condition, where participants had their usual sleep and (2) the sleep-deprived (SD) condition, where participants had 3 hours less sleep than their usual sleep, for 7 nights (amounting to 21 h of sleep debt). Measures included eye tracking performance and functional magnetic resonance imaging (fMRI). In each condition, each subject*s eye-position was monitored through 13 sessions, each with 46 trials, while fMRI data was recorded. There were two task performance measures, accuracy and response time. Accuracy measured the proportion of correct responses of all trials in each session. Response time measured the average amount of milliseconds until participants gazed at the target stimuli in each session. An experimental session could be treated as a short window. By splitting long trials of fMRI data into consecutive windows, Granger causality was applied based on short trials of fMRI data. This procedure helped to calculate pairwise causal influences with respect to time-varying property in brain causal interaction. Causal influence results were then averaged across sessions to create one matrix for each participant. This matrix was averaged within each condition to formulate a model of brain effective connectivity, which also served as a basis of comparison. In conclusion, significant effect of sleep deprivation was found on response time and brain effective connectivity. In addition, the change of brain effective connectivity after sleep deprivation was linked to the change of response time. First, an analysis of variance (ANOVA) showed significant difference for response time between the RW condition and the SD condition. No significant changes for accuracy were found. A paired t-test showed that response time was significantly shorter in sleep deprivation for the visual spatial sustained-attention task. Second, Granger causality analysis demonstrated a reduction of bidirectional connectivity and an increase of directed influences from low-level brain areas to high-level brain areas after sleep deprivation. This observation suggested that sleep deprivation provoked the effective connectivity engaged in salient stimuli processing, but inhibited the effective connectivity in biasing selection of attention on task and in maintaining self-awareness in day time. Furthermore, in the SD condition, attention at the visual spatial task seemed to be driven by a bottom-up modulation mechanism. Third, a relationship was found between brain effective connectivity with response time. Decreases of Granger causal influences in two directions, from medial frontal lobe to sub cortical gray nuclei and from medial parietal lobe to sub cortical gray nuclei, were associated with shorter response time in the SD condition. Additionally, an increase of Granger causal influence from medial parietal lobe to cerebellum was associated with longer response time in the SD condition.

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Approved for public release, distribution is unlimited / This study investigates the effects of reversing sleep-wake cycles on mood, sleep, and fatigue of the crewmembers and Air Wing 9 of the USS JOHN C. STENNIS (CVN-74). It also reviews the research conducted in sleep deprivation, circadian rhythms, shiftwork, fatigue, and mood. The effects of reversing sleep-wake cycle on mood of the crewmembers were analyzed by assessing a repeated administration of the Profile of Mood States (POMS). Mood states were monitored at three time points associated with the current work schedule (night shift vs. day shift) of the crewmembers. The results showed that younger participants were angrier than older participants on night shiftwork. The results also indicated that there was a significant interaction between repeated measures of mood states and gender. In addition, female participants reported significantly higher mood scale scores than the male participants, and topside participants were getting significantly less sleep than belowdecks participants. Given these findings, this area of research warrants further exploration. There is a significant need to educate military personnel of the effects of sleep deprivation and shiftwork on their job performance and individual health and safety. / Ensign, United States Navy

Approved for public release, distribution is unlimited / This study reports the initial findings of a four-year longitudinal study undertaken to assess the total amount of sleep received by cadets at the United States Military Academy. Specifically, data on the Class of 2007 were collected and analyzed during the freshman year. Survey data were collected (n=1290) on sleep habits prior to the cadets reporting to the Academy. Actigraphy data were collected (n=80) during summer military training and during the Fall academic semester. Survey data were analyzed using two different methods to determine total amount of sleep prior to reporting to the Academy ( x =8.5 hrs, s.d.=1.7 hrs; x =7.76 hrs, s.d.=1.46 hrs). Actigraphy data revealed that cadets received much less nighttime sleep (naps not included) during the Fall academic semester than they reported receiving in the month before CBT (total: x =5.32 hrs, s.d.=35.3 mins; school nights: x =4.86 hrs, s.d.= 37.4 mins; non-school nights: x =6.56 hrs, s.d.=64.4 mins). Using morningness/eveningness chronotypes, owls and non-owls differed significantly along the following dimensions: cadet attrition (z=2.66, p=0.0039), fall term academic quality point average (t=3.92, p<0.001), military program score (t=5.169, p<0.001), and physical program score (t=3.295, p=0.001). Suggestions for additional analysis of existing and subsequent data are proposed. / United States Military Academy, West Point, NY / Ensign, United States Naval Reserve

Approved for public release, distribution is unlimited / The Benefield Anechoic Facility (BAF), Edwards Air Force Base, California, is the largest anechoic military test facility in the world for testing developmental and operational electromagnetic equipment. Supervisors must often extend employees' work hours considerably in order to meet mission (i.e., test) timelines. Supervisors at the BAF currently have no accurate means of identifying when an employee's work performance is at risk of decreasing due to sleep deprivation, unbalanced circadian rhythms, and/or fatigue. Therefore, the focus of this research was to create a method for supervisors to effectively gauge the work performance levels of employees placed at risk for sleep deprivation. Thus, individual sleep data were collected for one week on eight volunteers at the BAF using assigned sleep monitoring devices known as Actigraphs. Extensive questionnaires were developed to determine volunteers' sleep pattern, demographics, and sleep history. For analysis purposes, the Fast Avoidance Scheduling Tool (FAST), based on the Sleep, Activity, Fatigue, and Task Effectiveness (SAFTE) model was used to determine how the performance level of each volunteer differed based on the amount of sleep acquired. The results demonstrated that as the week progressed and the volunteers' sleep decreased, the effectiveness of their work performance correspondingly decreased to a level where the safety of the test and the volunteers were both at risk. / Civilian, United States Air Force

Sleep deprivation is defined as an individual sleeping less than 6 hours per night. It is a common behavior amongst individuals who live in industrialized nations.Along with industrialization, its prevalence is also expected to rise with age. Despite this, there has been a shift in recent years with sleep deprivation increasing in the youth, likely related to the increased use of technology during the nighttime. Sleep deprivation and chronic sleep disruption are behaviors commonly observed amongst patients suffering from neurological and psychiatric disorders, like Alzheimer’s disease, Parkinson’s disease, depression, and anxiety. Many of these patients suffer from sleep disorders like insomnia, hypersomnia, and rapid eye movement sleep behavior disorder. It has long been thought that lack of sleep was caused by these disorders, yet there may be evidence to support a bidirectional relation between the two. We searched the literature to determine if there is a link between sleep disorders and sleep deprivation causing the exacerbation of these neurological and psychiatric disorders. Some studies support this hypothesis, for example, linking β-amyloid plaque buildup to lack of sleep, therefore increasing the risk of Alzheimer’s disease among chronically sleep deprived individuals. In this presentation we will take a closer look into the possible reasons as to why poor sleep may negatively impact cognitive health.