Helen C. Sing

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The negative effects of sleep deprivation on alertness and cognitive performance suggest decreases in brain activity and function, primarily in the thalamus, a subcortical structure involved in alertness and attention, and in the prefrontal cortex, a region subserving alertness, attention, and higher-order cognitive processes. To test this hypothesis, 17(More)
Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n = 18), 5 (n= 16), 7 (n = 16), or 9 h (n = 16) daily time in bed (TIB) for 7 days (restriction/augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed(More)
As both military and commercial operations increasingly become continuous, 24-h-per-day enterprises, the likelihood of operator errors or inefficiencies caused by sleep loss and/or circadian desynchrony also increases. Avoidance of such incidents requires the timely application of appropriate interventions--which, in turn, depend on the ability to measure(More)
This field-portable reaction time test and analysis software run on devices using the Palm operating system. It is designed to emulate a test and commercial device widely used in sleep deprivation, shift work, fatigue, and stimulant drug research but provides additional capabilities. Experimental comparisons with the standard commercial device in a 40-hour(More)
This study assessed the ability of high doses of caffeine to reverse changes in alertness and mood produced by prolonged sleep deprivation. Fifty healthy, nonsmoking males between the ages of 18 and 32 served as volunteers. Following 49 h without sleep, caffeine (0, 150, 300, or 600 mg/70 kg, PO) was administered in a double-blind fashion. Measures of(More)
This paper describes technical details of a computerized psychological test battery designed for examining the effects of various state-variables on a representative sample of normal psychomotor, perceptual and cognitive tasks. The duration, number and type of tasks can be customized to different experimental needs, and then administered and analyzed(More)
OBJECTIVE The effects of chronic partial sleep (sleep deprivation) and extended sleep (sleep augmentation) followed by recovery sleep on oculomotor function were evaluated in normal subjects to explore the usefulness of oculomotor assessment for alertness monitoring in fitness-for-duty testing. METHODS Sixty-six commercial drivers (24-62 years, 50m/16f)(More)
INTRODUCTION Oculomotor responses related to the pupil light reflex (PLR) and saccadic velocity may be sensitive to the effects of sleepiness and therefore could be used to evaluate an individual's fitness for duty. METHODS There were 12 normal subjects who completed an 8-d study. They were allowed 8 h in bed on the first three nights, 4 h in bed on the(More)
A study was conducted on the effects of 72 hours of sleep loss and modified continuous operations on performance and psychological variables. This paper presents the results of self-report data of 12 subjects for the following psychological variables: sleepiness, affect, motivation, cognitive difficulties, and waking dreams. The relationship between the(More)
Alpha-methyl-para-tyrosine (AMPT), a tyrosine hydroxylase inhibitor, was used to evaluate the physiologic role of central nervous system catecholamines in modulating alertness and mood. Forty healthy males were randomized to one of four conditions: AMPT in a rested condition; AMPT plus 40.5 hours of total sleep deprivation; placebo plus sleep deprivation;(More)