Effects of dawn simulation on markers of sleep inertia and post-waking performance in humans

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Abstract

To examine the effects of a simulated dawn during the last 30 min of sleep on the subsequent dissipation of sleep inertia and changes in simulated work and physical performance.

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Most cited references 21

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Role of melatonin in the regulation of human circadian rhythms and sleep.

C Cajochen, K Kräuchi, A Wirz-Justice (2003)

The circadian rhythm of pineal melatonin is the best marker of internal time under low ambient light levels. The endogenous melatonin rhythm exhibits a close association with the endogenous circadian component of the sleep propensity rhythm. This has led to the idea that melatonin is an internal sleep "facilitator" in humans, and therefore useful in the treatment of insomnia and the readjustment of circadian rhythms. There is evidence that administration of melatonin is able: (i) to induce sleep when the homeostatic drive to sleep is insufficient; (ii) to inhibit the drive for wakefulness emanating from the circadian pacemaker; and (iii) induce phase shifts in the circadian clock such that the circadian phase of increased sleep propensity occurs at a new, desired time. Therefore, exogenous melatonin can act as soporific agent, a chronohypnotic, and/or a chronobiotic. We describe the role of melatonin in the regulation of sleep, and the use of exogenous melatonin to treat sleep or circadian rhythm disorders.

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Effects of heat stress on cognitive performance: the current state of knowledge.

P A Hancock, I Vasmatzidis (2016)

This paper discusses the current state of knowledge on the effects of heat stress on cognitive performance. Although substantial research has been performed, it has proven difficult to describe the literature findings in a systematic manner. This is due to the large number of factors that come into play, such as task type, exposure duration, skill and acclimatization level of the individual and due to the absence of a concise theory on which experimental work can be based. However, two trends have been identified. First, heat stress affects cognitive performance differentially, depending on the type of cognitive task. Secondly, it appears that a relationship can be established between the effects of heat stress and deep body temperature. A number of exposure limits have been proposed during the last decades. These limits are summarized in this paper, with a special emphasis on the most recent one derived by Hancock and Vasmatzidis. This limit, which employs an attentional resource approach, defines exposure duration thresholds as parallel lines. Although this approach appears to be the most promising thus far, it is concluded that much remains to be understood before a limit becomes universally acceptable.

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Relationship between alertness, performance, and body temperature in humans.

Ann K. Wright, Joseph Hull, Charles Czeisler (2002)

Body temperature has been reported to influence human performance. Performance is reported to be better when body temperature is high/near its circadian peak and worse when body temperature is low/near its circadian minimum. We assessed whether this relationship between performance and body temperature reflects the regulation of both the internal biological timekeeping system and/or the influence of body temperature on performance independent of circadian phase. Fourteen subjects participated in a forced desynchrony protocol allowing assessment of the relationship between body temperature and performance while controlling for circadian phase and hours awake. Most neurobehavioral measures varied as a function of internal biological time and duration of wakefulness. A number of performance measures were better when body temperature was elevated, including working memory, subjective alertness, visual attention, and the slowest 10% of reaction times. These findings demonstrate that an increased body temperature, associated with and independent of internal biological time, is correlated with improved performance and alertness. These results support the hypothesis that body temperature modulates neurobehavioral function in humans.