The sensitivity of a palm-based psychomotor vigilance task to severe sleep loss

In this study, we evaluated the sensitivity of a 5-min personal digital assistant-psychomotor vigilance test (PDA-PVT) to severe sleep loss. Twenty-one participants completed a 10-min PVT-192 and a 5-min PDA-PVT at two hourly intervals during 62 h of sustained wakefulness. For both tasks, response speed and number of lapses (RTs > 500) per minute significantly increased with increasing hours of wakefulness. Overall, standardized response speed scores on the 5-min PDA-PVT closely tracked those of the PVT-192; however, the PDA-PVT was generally associated with more lapses/minute. Closer inspection of the data indicated that when the level of sleep loss and fatigue became more severe (i.e., Day 3), the 5-min PDA-PVT was not quite as sensitive as the 10-min PVT-192 when 2- to 10-sec foreperiods were used for both. It is likely, however, that the observed differences between the two devices was due to differences in task length. Thus, the findings provide further evidence of the validity of the 5-min PDA-PVT as a substitute for the 10-min PVT-192, particularly in circumstances in which a shorter test is required and/or the PVT-192 is not as practical.     

The effects of sleep deprivation on the attentional functions and vigilance

The study of sleep deprivation is a fruitful area of research to increase our knowledge of cognitive functions and their neural basis. In the current work, 26 healthy young adults participated in a sleep deprivation study, in which the Attentional Networks Test for Interactions and Vigilance (ANTI-V) was performed at 10a.m. after a night of normal sleep and again at 10 a.m. after 25.5-27.5 h of total sleep deprivation. The ANTI-V is an experimental task that provides measures of alerting, orienting and executive control attentional functions. Compared with previous versions, the ANTI-V includes a vigilance task, more reliable auditory alerting signals, non-predictive peripheral orienting cues, and also a neutral no-cue condition allowing the analysis of reorienting costs and orienting benefits. Thus, new evidence to evaluate the influence of sleep deprivation on attentional functioning is provided. Results revealed differences in both tonic and phasic alertness after sleep deprivation. Vigilance performance was deteriorated, while a warning tone was more helpful to increase participants' alertness, resulting in slightly faster RT and, in particular, fewer errors. The reorienting costs of having an invalid spatial cue were reduced after sleep loss. No sleep deprivation effect on the executive control measure was found in this study. Finally, since no control group was used, particular precautions were taken to reduce the influence of potential practice effects.     

Preliminary validation study of the 3-min wrist-worn psychomotor vigilance test

The 10-min psychomotor vigilance test (PVT) is a widely used tool to assess behavioral alertness. In operational environments, however, the 3-min version of the PVT is more practicable. Under controlled laboratory conditions, we compared performance on the 3-min PVT on a wrist-worn device with the 3-min PVT on a laptop computer. We conducted two repeated measures experiments (72 participants) to assess the effects of PVT device type (laptop or wrist-worn), backlight on the wrist-worn device (on or off), ambient light (low or normal levels), and interstimulus interval (ISI). First, we compared the wrist-worn PVT (ISI of 2–10 s) with the laptop-based PVT (ISI of 1–4 s). Participants performed six PVT trials counterbalanced for order of ambient light and device type. In both ambient-lighting conditions, the median differences in PVT metrics (reaction time, response speed, and percentage of 355-ms or 500-ms lapses combined with false starts) between the laptop and the wrist-worn PVT with the backlight on were less than 4.5 %. Specifically, the median difference in reaction times was less than 10 ms. However, the standard deviation in most metrics using the wrist-worn PVT was twice that of the laptop. In a second experiment, we compared the wrist-worn and laptop PVTs with the same ISIs (1–4 s) in normal light conditions. The results suggest that PVT data can be collected reliably in the field using the wrist-worn device with the backlight on and an ISI of 2–10 s.     

Effects of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance: comparison of horizontal and 6 degrees head-down bed rest

This study examined the effect of acute simulated microgravity on nocturnal sleep, daytime vigilance, and psychomotor performance. Each of 7 volunteers were maintained for 3 days of head-down and horizontal bed rest in a counter-balanced design. Assessment measures were polysomnographic recordings on the first night and performance on psychophysiological tasks on the second day involving subjective and objective vigilance, P300, simple reaction time tasks, and dual performance tasks. No clear difference in sleep structure was observed between the head-down and horizontal conditions, except for a slight decrease in Stage 4 for head-down. Both subjective and objective daytime vigilance, P300, and the simple RT task showed no statistical difference, although tracking performance on the dual task showed deterioration at 10:00 for the head-down condition. These results suggest that nocturnal sleep, daytime vigilance, and psychophysiological functions were not disturbed in head-down sleep conditions, although there was a mild deterioration of higher attentional function in the morning.     

The effects of chronic sleep reduction on the performance of cognitive tasks sensitive to sleep deprivation

In four sleep loss experiments we aimed, first, to compare performance during long-term sleep reduction with performance during short-term total sleep deprivation, and second, to measure the effects of both methods of sleep loss on ability to ignore distracting irrelevant stimuli, using a finding embedded figures test (FEFT). Logical reasoning, auditory vigilance and finding embedded figures tasks were shown to be significantly sensitive to one night's sleep deprivation. However, in one sleep reduction study subjects reduced to a mean of 5.2 hours sleep per night for 4 weeks showed no performance deficits on logical reasoning. In a second sleep reduction study subjects reduced to a mean of 4.3 hours sleep per night for 4 nights, and subjects reduced to a mean of 5.3 hours sleep per night for 18 nights, showed no performance deficits on logical reasoning or auditory vigilance, despite their reports of severe increases in subjective sleepiness and reduced concentration. Both these sleep reduction groups, though, did show decrements on the FEFT, which we interpret in terms of dearousal increasing distractibility, which the sleep-reduced subjects could not overcome with effort, as they did with the other tests.     

Effects of partial sleep deprivation: A comparative assessment of young non-professional and professional taxi drivers

AimThis study aims to determine the effects of partial sleep deprivation (PSD) on driving performance of professional and young non-professional drivers.MethodsThe study included fifty participants (20 professional taxi drivers and 30 young non-professional drivers) driving the simulator-cab in three conditions. The first test session (TS1) was conducted after one night of PSD followed by the second test (TS2) after two consecutive nights of PSD. The driving performance metrics in two conditions of PSD (i.e., sleep duration = 4.25 ± 0.5 h) were compared with the baseline drive with no sleep loss. Sleep restriction was monitored using Actiwatch. Drivers subjectively self-reported their alertness using Karolinska Sleepiness Scale (KSS). Driving performance metrics and reaction time to emergency events were collected during each drive.ResultsA preliminary mixed-design ANOVA showed deterioration in driving performance of all drivers in terms of speed (p < 0.1), speed variability (p = 0.06), standard deviation in lateral positions (SDLP) (p < 0.001) and delayed reaction time (p < 0.05). Separate Mixed-Effects Generalized Linear Models for professional and non-professional drivers showed that speed variability, SDLP and reaction time increased from baseline during both the PSD tests, among both the driving groups. The speed variability, SDLP and reaction time of professional drivers differed significantly from other drivers under PSD conditions. Contrary to the existing belief, the professional drivers had significant decrements in driving performance due to PSD.ConclusionA critical and comparative analysis revealed that driving experience/skill of professional drivers does not improve their resistance to deteriorating effects of sleep loss.     

Reliability of a computerized assessment of psychomotor performance and its sensitivity to alcohol-induced impairment

Two experiments examined a new computerized pursuit rotor task that measured psychomotor performance. Exp. 1 examined the acquisition and reliability of performance of 25 adults who performed the task on two sessions separated by a 2-wk. interval. Exp. 2 was a placebo-controlled test of task sensitivity to the performance-impairing effects of a 0.65 g/kg dose of alcohol. Exp. 1 showed that participants' performance was reliable over time. Exp. 2 showed that alcohol-impaired performance compared with placebo. The task could be useful for evaluating performance-impairing effects of other CNS depressant drugs, as well as complementing assessment batteries for research and instruction in studies of motor learning and human performance.     

Effects of task duration on sensitivity to sleep deprivation using the multi-attribute task battery

Several factors affect the sensitivity to sleep deprivation in the performance of computerized tests. Two of these are task complexity and duration. Complexity can improve sensitivity by increasing the demands required to complete the task, but it can also decrease sensitivity by improving the subject’s motivation. The effects of task duration are more predictable in that longer tests generally are more susceptible to deprivation effects than shorter ones. The impact of task duration on an interesting, but complex, aviation simulation was examined here. By breaking down data from 30-min multi-attribute task battery administrations into the first, second, and third 10 min of performance, it was shown that tests shorter than 30 min underestimate the impact of sleep loss on performance. This was especially evident in measures of time-out and tracking errors.     

Personality as a predictor of the objective and subjective impact of sleep deprivation

Although, impairments following sleep deprivation have been clearly demonstrated in the literature, researchers have found a wide range of individual variation in response to sleep deprivation. The relationship between personality and the subjective and objective impact of sleep deprivation was examined using the Epworth Sleepiness Scale, Stanford Sleepiness Scale, Sleep Hygiene Index, Profile of Mood States, an oddball reaction time test, a multi-task cognitive performance battery (SynWin), and the NEO Personality Inventory Revised. Subjects (14 males, 14 females, mean age 20.5) were sleep deprived for 28–35 h and during this time were allowed access to self-reported typical amounts of tobacco, caffeine, and food. Post sleep deprivation: (a) higher neuroticism scores were related to participants feeling sleepier, experiencing more mood disturbance, and performing inferiorly on a behavioral task; (b) subjects scoring as introverts showed more compromised behavioral performance compared to extraverts. The authors suggest that potential moderating variables of the relationship between personality and sleep deprivation such as stimulant use, food intake, and socialization warrant further investigation.     

A new quantitative approach to the assessment of stages of vigilance as defined by spatiotemporal EEG patterning

Electroencephalographically oriented research on vigilance needs valid measures for assessing the level of vigilance between wakefulness and sleep. When studying different psychologically, psychopathologically, and pharmacologically induced states, special attention has to be paid to minor alterations of the level of vigilance which are reflected, essentially, in topographical changes of alpha-activity (Stage A). Since vigilance is a dynamic process, brief fluctuations in the range of a few seconds must also be recorded. In our opinion existing methods of quantification do not fully meet these demands. We have, therefore, developed a relatively simple procedure which can be characterized as an attempt quantitatively to reconstruct visually, i.e., spatiotemporally defined patterns of vigilance. The usefulness of this method, which also has certain limitations, has been demonstrated in psychopharmacological studies.     

Sleep deprivation and stressors: Evidence for elevated negative affect in response to mild stressors when sleep deprived

Stress often co-occurs with inadequate sleep duration, and both are believed to impact mood and emotion. It is not yet known whether inadequate sleep simply increases the intensity of subsequent stress responses or interacts with stressors in more complicated ways. To address this issue, we investigated the effects of one night of total sleep deprivation on subjective stress and mood in response to low-stress and high-stress cognitive testing conditions in healthy adult volunteers in two separate experiments (total N = 53). Sleep was manipulated in a controlled, laboratory setting and stressor intensity was manipulated by changing difficulty of cognitive tasks, time pressure, and feedback about performance. Sleep-deprived participants reported greater subjective stress, anxiety, and anger than rested controls following exposure to the low-stressor condition, but not in response to the high-stressor condition, which elevated negative mood and stress about equally for both sleep conditions. These results suggest that sleep deprivation lowers the psychological threshold for the perception of stress from cognitive demands but does not selectively increase the magnitude of negative affect in response to high-stress performance demands. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Comparison of Griffiths-II and Bayley-II tests for the developmental assessment of high-risk infants

IntroductionTwo important risk factors for abnormal neurodevelopment are preterm birth and neonatal hypoxic ischemic encephalopathy. The new revisions of Griffiths Mental Development Scale (Griffiths-II, [1996]) and the Bayley Scales of Infant Development (BSID-II, [1993]) are two of the most frequently used developmental diagnostics tests. The Griffiths-II is divided into five subscales and a global development quotient (QD), and the BSID-II is divided into two scales, the Mental scale (MDI) and the Psychomotor scale (PDI).The main objective of this research was to establish the extent to which developmental diagnoses obtained using the new revisions of these two tests are comparable for a given child.Material and methodsRetrospective study of 18-months-old high-risk children examined with both tests in the follow-up Unit of the Clinic of Neonatology of our tertiary care university Hospital between 2011 and 2012. To determine the concurrent validity of the two tests paired t-tests and Pearson product-moment correlation coefficients were computed. Using the BSID-II as a gold standard, the performance of the Griffiths-II was analyzed with receiver operating curves.Results61 patients (80.3% preterm, 14.7% neonatal asphyxia) were examined. For the BSID-II the MDI mean was 96.21 (range 67–133) and the PDI mean was 87.72 (range 49–114). For the Griffiths-II, the QD mean was 96.95 (range 60–124), the locomotors subscale mean was 92.57 (range 49–119). The score of the Griffiths locomotors subscale was significantly higher than the PDI (p < 0.001). Between the Griffiths-II QD and the BSID-II MDI no significant difference was found, and the area under the curve was 0.93, showing good validity. All correlations were high and significant with a Pearson product-moment correlation coefficient >0.8.ConclusionsThe meaning of the results for a given child was the same for the two tests. Two scores were interchangeable, the Griffiths-II QD and the BSID-II MDI.     

Affective responses to 10-minute and 30-minute walks in sedentary,overweight women: Relationships with theory-based correlates of walking for exercise

ObjectivesThe purpose of this study was to examine affective responses to 10-min and 30-min walks among sedentary, overweight women. Secondary purposes were to: a) examine differences in theory-based correlates of future participation in walking for exercise; and b) determine if the affective responses were related to these correlates.Design/MethodsTwenty-three sedentary, overweight women (M age = 26.62 years; BMI = 33.53 kg/m²) completed 10-min walk, 30-min walk, and quiet rest (QR) control conditions. Affective responses were assessed prior to, during, and following each condition. Self-efficacy and intention for regular participation in multiple 10-min walks or single 30-min walks for exercise during the next month were also assessed post-exercise.Results/ConclusionsAnalyses revealed that improvements in affective responses (p < 0.05) emerged during and following both walking sessions while no benefits were observed with QR. Self-efficacy (p < 0.01) and intention (p < 0.01) to walk for exercise in the future were significantly higher for multiple 10-min walks. Correlation analyses demonstrated that affective responses were most strongly and consistently correlated with intention and self-efficacy for future participation following the 10-min walk. These findings demonstrate that, while both walks resulted in similar affective benefits, sedentary, overweight women reported greater intention and self-efficacy to participate in multiple brief walks for exercise in the future.     

Spatial and reversal learning in the Morris water maze are largely resistant to six hours of REM sleep deprivation following training

This first test of the role of REM (rapid eye movement) sleep in reversal spatial learning is also the first attempt to replicate a much cited pair of papers reporting that REM sleep deprivation impairs the consolidation of initial spatial learning in the Morris water maze. We hypothesized that REM sleep deprivation following training would impair both hippocampus-dependent spatial learning and learning a new target location within a familiar environment: reversal learning. A 6-d protocol was divided into the initial spatial learning phase (3.5 d) immediately followed by the reversal phase (2.5 d). During the 6 h following four or 12 training trials/day of initial or reversal learning phases, REM sleep was eliminated and non-REM sleep left intact using the multiple inverted flowerpot method. Contrary to our hypotheses, REM sleep deprivation during four or 12 trials/day of initial spatial or reversal learning did not affect training performance. However, some probe trial measures indicated REM sleep-deprivation-associated impairment in initial spatial learning with four trials/day and enhancement of subsequent reversal learning. In naive animals, REM sleep deprivation during normal initial spatial learning was followed by a lack of preference for the subsequent reversal platform location during the probe. Our findings contradict reports that REM sleep is essential for spatial learning in the Morris water maze and newly reveal that short periods of REM sleep deprivation do not impair concurrent reversal learning. Effects on subsequent reversal learning are consistent with the idea that REM sleep serves the consolidation of incompletely learned items.     

The effects of total sleep deprivation on the generation of random sequences of key-presses, numbers and nouns

According to a recent hypothesis, executive functions should be particularly vulnerable to the effects of total sleep deprivation. Random generation is a task that taps executive functions. In three experiments we examined the effects of total sleep deprivation on random generation of keypresses, numbers, and nouns, in particular on the suppression of prepotent responses and the selection of next responses by way of applying a local-representativeness heuristic. With random key-presses suppression of prepotent responses did not suffer from lack of sleep, but it became poorer at a sufficiently high pacing rate. In contrast, suppression of prepotent responses suffered when numbers and nouns were generated. According to these findings different types of random generation tasks involve different types of inhibitory process. With only four response alternatives, but not with larger response sets, application of the local-representativeness heuristic was impaired after a night without sleep. In terms of a simple formal model, serial-order representations of the preceding responses are used in selecting the next response only for the small response set, and not for larger response sets. Thus, serial-order representations are likely to suffer from loss of sleep. These findings strongly suggest that random generation involves multiple processes and that total sleep deprivation does not impair all sorts of executive functions, but only some.     

The effects of total sleep deprivation on semantic priming: Event-related potential evidence for automatic and controlled processing strategies

There is general consensus that performance on a number of cognitive tasks deteriorates following total sleep deprivation. At times, however, subjects manage to maintain performance. This may be because of an ability to switch cognitive strategies including the exertion of compensatory effort. The present study examines the effects of total sleep deprivation on a semantic word priming task. Word priming is unique because it can be carried out using different strategies involving either automatic, effortless or controlled, effortful processing. Twelve subjects were presented with word pairs, a prime and a target, that were either highly semantically associated (cat…dog), weakly associated (cow…barn) or unassociated (apple…road). In order to increase the probability of the use of controlled processing following normal sleep, the subject’s task was to determine if the target word was semantically related to the prime. Furthermore, the time between the offset of the prime and the onset of the target was relatively long, permitting the use of an effortful, expectancy-predictive strategy. Event-related potentials (ERPs) were recorded from 64 electrode sites. After normal sleep, RTs were faster and accuracy higher to highly associated targets; this performance advantage was also maintained following sleep deprivation. A large negative deflection, the N400, was larger to weakly associated and unassociated targets in both sleep-deprived and normal conditions. The overall N400 was however larger in the normal sleep condition. Moreover, a long-lasting negative slow wave developed between the offset of the prime and the onset of the target. These physiological measures are consistent with the use of an effortful, predictive strategy following normal sleep but an automatic, effortless strategy following total sleep deprivation. A picture priming task was also run. This task benefits less from the use of a predictive strategy. Accordingly, in this task, ERPs following the target did not differ as a function of the amount of sleep.     

Rats (Rattus norvegicus) modulate eating speed and vigilance to optimize food consumption: effects of cover, circadian rhythm, food deprivation, and individual differences.

The eating behavior of rats (Rattus norvegicus) given food pellets of specified size was examined as a function of environmental, circadian, and experiential influences. Eating times were shorter in lighted, exposed environments than in dark, covered environments, even though in novel, exposed conditions the rats made many scanning movements as they ate. Eating time also varied as a function of the circadian cycle in that eating times were shorter in the night portion of the day-night cycle. Finally, eating times decreased if rats were food deprived, and deprivation had a small but enduring influence. Within the tests there were differences in the eating times of individual rats that were not attributable to the experimental manipulations. That rats can optimize food intake by varying eating speed is discussed in relation to physiological regulation of feeding and to optimal foraging theory.