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An English language self-assessment Morningness-Eveningness questionnaire is presented and evaluated against individual differences in the circadian vatiation of oral temperature. 48 subjects falling into Morning, Evening and Intermediate type categories regularly took their temperature. Circadian peak time were identified from the smoothed temperature(More)
Few sleep deprivation (SD) studies involve realism or high-level decision making, factors relevant to managers, military commanders, and so forth, who are undergoing prolonged work during crises. Instead, research has favored simple tasks sensitive to SD mostly because of their dull monotony. In contrast, complex rule-based, convergent, and logical tasks(More)
Historical evidence suggests that sleep deprivation affects temporal memory, but this has not been studied systematically. We explored the effects of 36 hr of sleep deprivation on a neuropsychological test of temporal memory. To promote optimal performance, the test was short, novel, and interesting, and caffeine was used to reduce "sleepiness". A total of(More)
Low frequency (< 1 Hz) delta EEG in sleep is of increasing interest as it indicates cortical reorganization, especially in the prefrontal cortex (PFC). Other research shows that delta power in sleep is positively linked to waking cerebral metabolic rate. Such findings suggest that < 1 Hz activity may reflect waking performance at neuropsychological tests(More)
Although much is known about the impact of sleep loss on many aspects of psychological performance, the effects on divergent ("creative") thinking has received little attention. Twelve subjects went 32 h without sleep, and 12 others acted as normally sleeping controls. All subjects were assessed on the figural and verbal versions of the Torrance Tests of(More)
Neuropsychological testing and brain imaging show that healthy aging leads to a preferential impairment of the prefrontal cortex (PFC). Interestingly, in young adults sleep deprivation (SD) has similar effects. Psychological tasks not so oriented to the PFC are less sensitive both to SD and aging. The PFC is a cortical region working particularly hard(More)
Recent findings with clinically oriented neuropsychological tests suggest that one night without sleep causes particular impairment to tasks requiring flexible thinking and the updating of plans in the light of new information. This relatively little investigated field of sleep deprivation research has real-world implications for decision makers having lost(More)
Driver sleepiness is a major cause of serious road crashes. Coffee is often used as an effective countermeasure to driver sleepiness. However, the caffeine levels in coffee are variable, whereas certain proprietary "functional energy drinks" (FEDs) contain known levels of caffeine (and other ingredients). We investigated the effectiveness of a well-known(More)
The efficacy of putative "in-car" countermeasures to driver sleepiness is unknown. Sixteen young adult drivers within the normal range for the Epworth Sleepiness Scale (ESS), had their sleep restricted to 5 hours the night before, and drove an interactive car simulator in the afternoon for 2.5 hours, under monotonous conditions. After 30 minutes of driving(More)