Oculomotor measures as predictors of performance during sleep deprivation.

INTRODUCTION: Studies have indicated that working under sleep deprivation conditions results in deficits in performance on various tasks. Few studies, however, have attempted to find a measure for predicting performance changes under sleep deprivation conditions. The current study examined whether oculomotor measures could predict changes in performance under non-sleep deprivation and acute short-term sleep deprivation conditions. METHODS: Oculomotor measures and performance were examined during five testing sessions in each study. In the non-sleep deprivation study (N = 23) the testing sessions took place during 2 consecutive days. The sleep deprivation study (N = 26) took place in an 18-h sustained operations period during the night of sleep deprivation. RESULTS: Under non-sleep deprivation conditions, pupil diameter significantly predicted performance on grammatical reasoning (B = 0.360) and constriction latency significantly predicted performance on combined tasks (B = 0.182). Under sleep deprivation conditions, diameter, constriction latency, and saccadic velocity significantly predicted performance on a psychomotor vigilance task (B = -21.002, B = -23.126, B = -18.028, respectively). Overall, oculomotor measures better predicted performance changes under sleep deprivation conditions and better predicted performance decrements on vigilance-based tasks than cognitive tasks under acute sleep deprivation conditions. DISCUSSION: The current research suggests saccadic velocity and pupil diameter may be the most useful predictors of performance under sleep deprivation conditions, perhaps because these measures are largely controlled by involuntary neural components that slow during sleep deprivation. These data support research suggesting that saccadic velocity and pupil diameter detect excessive sleepiness and predict performance decrements under sleep deprivation conditions using additional oculomotor measures and a non-sleep deprivation comparison group.

Blood pressure increases during a simulated night shift in persons at risk for hypertension.

BACKGROUND: Shift work with sleep disruption is a systemic stressor that may possibly be associated with blood pressure dysregulation and hypertension. PURPOSE: We hypothesize that rotation to a simulated night shift with sleep deprivation will produce blood pressure elevations in persons at risk for development of hypertension. METHOD: We examined the effects of a simulated night shift on resting blood pressure in 51 diurnal young adults without current hypertension. Resting blood pressure was monitored throughout a 24-h period of total sleep deprivation with sustained cognitive work. Twelve participants (23.5%) reported one or more parents with a diagnosis of hypertension. Ten participants were classified as prehypertensive by JNC-7 criteria. Only two prehypertensive subjects reported parental hypertension. RESULTS: Results indicate that, as the night shift progressed, participants with a positive family history of hypertension showed significantly higher resting diastolic blood pressure than those with a negative family history of hypertension (p = 0.007). Prehypertensive participants showed elevated blood pressure throughout the study. CONCLUSION: These data suggest that rotation to a simulated night shift with sleep deprivation may contribute to blood pressure dysregulation in persons with a positive family history of hypertension.

Perception of robot passability with direct line of sight and teleoperation.

OBJECTIVE: To examine participants' abilities to judge the passability of robots through apertures in direct-line-of-sight (DLS) and teleoperation (TO) conditions, two experiments were conducted. BACKGROUND: Past work has demonstrated that operators find it difficult to perceive aspects of remote environments during TO. For example, urban search-and-rescue operators have experienced difficulty judging whether a robot could pass through openings or over obstacles. Although previous research has discussed perceptual difficulties in TO, the differences between DLS and TO have not been quantified. METHOD: In the first experiment, participants judged the smallest passable aperture widths for three robot sizes for both DLS and TO conditions. In the second experiment, aperture widths were judged for three camera heights and two robot distances during TO. RESULTS: In the DLS condition, participants produced similar judgments for the three robot sizes using dimensionless measurements. In the TO condition, participants' judgments were more variable and they judged smaller apertures as passable. CONCLUSION: Overall, participants judged apertures that were too small for the robot to pass as passable. This tendency was more pronounced in four instances: as robot size increased, during TO, when the camera was at its lowest height, and as distance between the robot and the aperture increased. APPLICATION: Judgments of passability help to quantify differences in perception between DLS and TO. These results will be useful in the design of training regimes for TO tasks. Increasing operator understanding of performance differences under varying conditions will lead them to be more accurate when making critical decisions in remote environments.

Language performance under sustained work and sleep deprivation conditions.

INTRODUCTION: Although substantial research has been completed on the effects of sleep deprivation on performance, very little research has focused on language-based tasks. The purpose of the current study was two-fold: 1) to determine the extent to which short-term sleep deprivation affects language performance; and 2) to examine whether relatively short and easy-to-administer "probe" tasks could signal decrements in language performance under sleep deprivation conditions. METHODS: There were 38 non-native English-speaking students who were paid to complete a 28-h sleep deprivation study. The participants completed several potential cognitive and vigilance probe tasks and a variety of language-based tasks. Each task was administered four times, once in each testing session during the night (18:30-22:30, 23:00-03:00, 03: 30-07:30, and 08:00-12:00). All tasks were counterbalanced across the testing sessions. RESULTS: Repeated-measures ANOVAs indicated that language tasks that required sustained attention and higher level processing (e.g., reading comprehension) were negatively affected by sleep deprivation, whereas other tasks that relied primarily on more basic language processing (e.g., antonym identification) were not affected. Hierarchical linear modeling analyses assessed how well the probe tasks predicted language performance. These results indicated that performance accuracy and/or speed on many of the probe tasks predicted decrements in language performance. CONCLUSIONS: These findings suggest that sustained work conditions and sleep deprivation negatively affect some types of language performance. Moreover, the use of probe tasks indicates that easy-to-administer tasks may be useful to identify when detriments are likely to occur in language-based performance under sleep deprivation conditions.